(Homotopy) Y ENR and contractible subset implies Y is a retract

Question: I'm trying to solve the following question:
Suppose $Y \subset R^n$ is a Euclidean neighborhood retract. I want to prove that if $Y$ is contractible, then it is a retract of $R^n$.
Answer: Let me solve the case of compact $Y$. Thus $Y$ is a contractible ANR. Then Y is an AR.
Indeed, the equivalence  "contractible ANR $\Leftrightarrow$ AR"  is a well known theorem, certainly known in the past to the founder of the theory of ANRs, Karol Borsuk. To prove this equivalence, consider an arbitrary compact metric space $X$, its closed subset $A$, and an arbitrary continuous map $f : A \rightarrow Y$, where $Y$ is a contractible ANR. Let  $H:Y\times[0;1]\rightarrow Y$  be a contraction to a point  $p\in Y$, meaning that  $H(y\ 0)=p$  and  $H(y\ 1)=y$  for every  $y\in Y$. Now we get the constant map  $g_0:X\rightarrow Y$,  such that  $\forall_{x\in X}\ g_0(x)=p$,  and a homotopy  $\Phi : A\times [0;1]\rightarrow Y$ defined by:
$$\forall_{a\in A}\forall_{t\in [0;1]}\quad \Phi(a\ t) := H(f(a)\ t)$$
Observe that  $\forall_{a\in A}\ \ g_0(a)=\Phi(a\ 0)$. Thus by the Borsuk homotopy extension theorem there exists a homotopy  $F:X\times [0;1]\rightarrow Y$  such that

$\forall_{x\in X}\quad F(x\ 0)=g_0(x)$     (the value is  $p$,  of course)
$\forall_{a\in A}\forall_{t\in [0;1]}\quad F(a\ t) = \Phi(a\ t)$

Now define  $g_1:X\rightarrow Y$  by  $\forall_{x\in X}\ \ g_1(x) := F(x\ 1)$.  Then  $g_1$  is a continuous extension of  $f:A\rightarrow Y$  onto $X$. Thus we have proven that $Y$ is an AR.
It follows that $Y$ is a retract of the whole $\mathbf R^n$. Indeed, space $Y$--being an AR--is a retract of a cube  $Q := [-\alpha;\alpha]^n$  which contains $Y$, while cube $Q$  is a retract of $\mathbf R^n$.
REMARK  The last argument was simple, correct and adequate but ad hoc. Here is a more basic (general) argument: let compact $Y\subseteq \mathbf R^n$ be and AR (for metric compact spaces). The Euclidean space $\mathbf R^n$ is a subspace of a metric compact space $C$ (e.g. of  $\mathbf R^n\cup\{\infty\} = \mathbf S^n$),  and $Y$ is a retract of $C$, hence $Y$ is a retract of $\mathbf R^n$.
Comment: One may get their first taste of the retractions+AR+ANR topic from the elegant Appendix of the Eilenberg-Steenrod classic monograph on the foundations of the Algebraic Topology.
Comment: In addition to the monograph "Theory of Retracts" by K.Borsuk, there is also a monograph by S.T.Hu (the same Hu, who authored a beautiful monography on the Homotopy Theory).. These monographs complement each other well.

(Do I really have to copy, delete, paste and edit my comment in ordere to correct one silly typo?)
Comment: Thanks for thw answer! I don't know another way to correct a typo..
Answer: Observe that any retract of $\newcommand{\RR}{\mathbb{R}} \RR^n$ is necessarily a closed subspace of $\RR^n$. Assuming this necessary condition, the answer to the question is affirmative. More precisely, if $Y$ is a contractible ANR (absolute neighbourhood retract) and a closed subspace of $\RR^n$, then $Y$ is a retract of $\RR^n$. This is an instance of the following result.
Claim:
Let $X$ be a metrizable ANR, and let $Y$ be an ANR and a closed subspace of $X$.
If the inclusion of $Y$ into $X$ is a homotopy equivalence, then $Y$ is a retract of $X$.
This claim is an immediate consequence of the next two propositions.
Proposition 1:
Let $X$ be a metrizable ANR, and let $Y$ be a closed subspace of $X$.
If $Y$ is an ANR, then the inclusion of $Y$ into $X$ is a cofibration.
This is stated as proposition A.6.7 in the appendix to Fritsch and Piccinini's book "Cellular structures in topology", page 282. It is also stated and proved in Sze-Tsen Hu's 1965 book "Theory of retracts": see theorem 3.2 and corollary 3.3 on pages 120 and 121. Alternatively, you may look at the single lemma and its proof in this other answer, which gives proposition 1 for the case of ENRs.
Proposition 2:
Assume $Y$ is a subspace of $X$ such that the inclusion of $Y$ into $X$ is a cofibration and a homotopy equivalence.
Then $Y$ is a strong deformation retract of $X$; in particular, $Y$ is a retract of $X$.
This is a standard result in basic homotopy theory. For example, it is stated and proved as corollary 0.20 in chapter 0 of Allen Hatcher's book "Algebraic topology".


Does using a transparent screen protector for the face and the back of the iPhone 4 have drawbacks?

Question: I saw multiple videos that the iPhone 4 screen can not be scratched by keys, coins and is even quite resistant to dropping. What are the drawbacks to adding this layer of protection (in general or perhaps for a specific film you have used) so I can weigh whether I wish to use one?
Answer: In the end, the worth of a case/screen protector is entirely up to you.
The iPhone 4/4S screen is incredibly durable, and without a protector, I've had mine since the release of the 4S and it's only got the smallest micro-buffs in the screen (you really have to be looking at them to see it).
I'd say the only real good reason for protection of any kind is to protect your device from drops. Being that they're a specially treated glass, if you drop it from a sizeable distance, they'll more than likely shatter.
Answer: Apple made big improvements with the latest iPhone screens. I've had the iPhone 4s since for a while now (since it came out) and I'm notoriously hard on my phones, but the screen still looks as good as new. Personally I find the plastic screen covers just annoying, they always come off and they're a pain to apply. Hope that helps.
Answer: I've been using a transparent protector since I had my first iPhone (4 years ago) and I can only recommend it. If you buy a decent one, you won't even notice it's there.
I agree Apple has made a lot of improvements on the durability of the iPhones, but the protectors has always kept my iPhones next to brand new (which has come handy when I sold my iPhone).
And these days, you can buy 10 protectors for less then $10, so in my opinion, this is a very small amount to pay to keep my iPhone scratch-less.
Answer: I agree that screen protectors are quite necessary, but not only for just resisting scratches.  The ones I have used for years (ScreenGuardz) have an anti-glare feature which is nice to have in bright situations and they are less prone to collecting fingerprints all over the screen.
The decent ones cost a bit more (still inexpensive) but are still worth it.  Here's the ScreenGuardz link...
ScreenGuardz - iPhone
Check for them on eBay though, they might have new ones for cheaper.  ;)
But, if you have already picked up scratches on your touch screen panel, then make sure to use the right buffing agent for your specific screen to work out the scratches.  Touch screen panels vary in their composition (Glass, Acrylic, Gorilla Glass, etc.) so be sure you use the right one.  These guys have a line of buffing compounds specifically for mobile device touch panels so you might look them up...
TDI-LLC Technology - Glass, Acrylic, and Gorilla Glass Compounds


Anti virus / Anti malware software

Question:
Possible Duplicate:
Is scanning VIRUS needed on Linux Distros?

Do I need anti virus / anti malware software?
Which sw do you recomend?
Where do I get it?
Im new to Ubuntu.
Comment: Exact Duplicate of: Is scanning VIRUS needed on Linux Distros?: http://askubuntu.com/questions/10373/is-virus-scanning-needed-on-linux-distros
Comment: Lol, Umbuntu. Sounds like a kids drink.
Answer: A virus scanner is currently not needed. There exist an estimated 200 viruses for Linux, a handful of which are supposed to work on contemporary distributions. But they are unlikely to be encountered in practice. Most of that malware are worms which are targetting servers only.
Anyway, you will need a virus scanner anyway, if you use wine and thus download freeware windows software. Windows viruses may run under the windows emulater. Not all of them work, but some of them could cause harm and even damage/leak personal files.
Secondly, if you interface with Windows users, for example at your workplace. You will need a virus scanner to check devices, because otherwise people might end up accusing you of spreading viruses (even though it are Windows viruses that couldn't possibly originate on your Linux computer). It's a bit like getting a flu shot to not endanger the community around you.
TL;DR: use regardless of practical need
Answer: There is no need for an antivirus/antiWhatever in Linux. About 99% of all announcements related to using an antivirus for linux are FUD (Fear Uncertainty Doubt) coming from tipically private corporations (Cough...wont say the main one.. cough.. cough)
But anyway the ONLY way to have a antivirus in Linux would be if you are for example a MAIL SERVER. In which case you would need ClamAV for example so that it checks the mail for your customers. Of course, assuming you have windows customers in your Mail Server.
So to get to the point, you will only need an Antivirus if you are hosting some kind of service for Windows users.
NOTE - The speed at which a solution is found for a vulnerability in linux is many times higher than the total work combine of Windows programmers. Specially if it is an open source project, in which you CAN see how to fix stuff quickly.
Answer: No it's not really needed. There is ClamAV but, I think it is used only to protect other Windows machines.
Answer: What I recommend instead of antivirus software is to make sure your machine is behind a firewall, or you have the firewall enabled in Ubuntu. If you are running a server make sure inbound access is only allowed on services you're providing.
While Linux by design is much more secure than say, Windows, you're still vulnerable to exploits on any of the network services running on your machine. I've seen a few boxes exploited in my day, and some attacks can be pretty sophisticated and hide themselves very well (i.e. they recompile a version of ps that hides the trojan processes). In those situations, usually your best bet is to reformat and start from scratch.
Answer: I have avast free edition for ubuntu on my system but it is basically for to scan my windows drive just in case it gets infected it would be easier to check for viruses from ubuntu , I have windows and ubuntu dual boot

Anti virus / Anti malware software


about UFS allocation on FreeBSD

Question: I am wondering what allocation method does UFS use?
I know there are several options: contiguous, linked allocation and indexed allocation.
Which one is for UFS?
Answer: The details are in the paper A Fast File System for UNIX:

The bit map of available blocks in the cylinder group replaces the traditional file system's free list.
Answer: Your example terms don't coincide with anything I'm familiar with in file systems. The two proper forms of allocations I know of relate to disk space and inodes.
Where disk space is concerned, the two key forms for traditional file systems are extent-based and block-based. UFS is block-based.
Inodes are allocated statically (i.e., at file system creation time) or dynamically. UFS allocates inodes statically.
Does your question refer to some other facet of UFS, perhaps?

about UFS allocation on FreeBSD


Variance of exponential random variable

Question: For a random variable $\xi$, what bounds can be achieved for Var $e^{\xi}$ in terms of E$\xi$ and Var $\xi$?
Comment: Unfortunately, this question is a poor fit for this site since it is not research-level. You'd be better off asking this at math.stackexchange.com. At any rate, you might ponder the following two examples first: Let $X_1 = c$ almost surely for some $c \in \mathbb R$ and, let $X_2 = \exp(Y)$ where $Y$ has a Pareto distribution, i.e., with pdf $f(y) = \alpha y^{-\alpha-1}$ for all $y \geq 1$ and some $\alpha > 0$.
Answer: None.
Even if $X$ takes only two values, one of which with very small probability, Var$(e^X)$ can be made arbitrarily small or large.
Answer: Here's a different way to think about your question, using the cumulant-generating function $c(\theta) \equiv \log \operatorname{\mathbb{E}} e^{\theta \xi}$.  To visualize this function, note that CGFs (i) always go through the origin (obviously) and (ii) are always convex (by the Cauchy-Schwarz inequality).
What you're asking for is a bound on var $e^{\xi}$, or $e^{c(2)} - e^{2 c(1)}$ in CGF notation.  Properties (i) and (ii) alone tell us the (unsurprising!) fact that $c(2)$ is at least $2c(1)$, and is strictly greater than $2c(1)$ if $\xi$ has nonzero variance.
So the question is what you can say about the relationship between $c(2)$ and $2c(1)$ based on the extra information you're given about the first cumulant (mean) and second cumulant (variance) of $\xi$.  Translating into CGF terms, this extra information corresponds to the first and second derivatives of $c(\cdot)$ at the origin, $c'(0)=\operatorname{\mathbb{E}} \xi$ and $c''(0)=\operatorname{var} \xi$.  The problem that cardinal and Omer are pointing out is that if there's weird stuff going on in the higher cumulants (or equivalently moments), then there's a lot of room for flexibility in the higher derivatives at zero, $c'''(0)$, $c''''(0)$, and so on.  This means you can get a lot of convexity in $c(\cdot)$ away from the origin, and hence there's basically nothing you can say, without further assumptions, about the gap between $c(2)$ and $2c(1)$.

Here's a picture.  The slope of the CGF at the origin is negative, reflecting the fact that $\operatorname{\mathbb{E}} \xi$ is negative in this example.  The curvature at the origin measures variance.  Higher cumulants, reflected in higher order derivatives at the origin, make their presence felt via the "extra" (beyond quadratic) convexity that starts to become visible around $\theta=1$.  The picture is drawn for an example in which var $e^{\xi}$ is finite, i.e. $c(2)$ is finite, which need not be the case in general.
Perhaps thinking in these terms will help you figure out what extra constraints you might need to put on your problem to be able to put bounds on var $e^{\xi}$?  One final remark: your terminology ("exponential random variable") is rather misleading.

Variance of exponential random variable


Why did I loose my internet connection after installing a VPN client?

Question: I installed the VPN client to connect to my company's network, the Cisco AnyConnect SSL VPN client.
Everything went fine, I was able to install it correctly, connect to the server, was prompted for my username and password.
Then after I clicked on accept the terms and conditions, it looked like I was connected to the VPN for a few seconds, and then I got brutally disconnected from the VPN.
That's when I started having trouble. Basically since then, I have not been able to access even the regular internet anymore at all! The weird thing is that I still see myself as connected to my wireless network like always, but if I try to access any page with any browser it won't load because of a DNS issue I would assume.
I have tried restarting, killing any VPN process I would see, but this hasn't solved my issue.
Note that I have another laptop in the same room using the same wireless, and accessing the network just fine.
Also, not sure if this is related or not, but since this VPN issue, when I restart the laptop I get a "beep" when it boots saying my battery and AC type is not recognized and that battery may not charge (even though it seems to charge fine), is it something I should worry about?
I am using ubuntu 12.04, I have no idea how to diagnose what's wrong, so any help would be appreciated.
At this point I don't really care about the VPN anymore, I just want to get my regular connection back!
Answer: Make a new connection via the wireless manager; this sometimes fixes the problem.


Accidently retracted two solutions, but timer is not running

Question: I've accidently retracted two solutions from the farm in WSS3 but luckily the timer is not running so the jobs did not run. Now when I go to Solution Management I see "Error" for their deployment statuses. I would like to retract the retraction so to speak and cancel the jobs so that when the timer does run, they do not get retracted. How can I do this?
Answer: There is no "cancel" method on SPSolution's.
If you still have the solution file(s) you can just add the solution again and re-i stall it. First you should start timer job and finish the retraction, and remove solutions though...
Answer: Just try this command in SharePoint Management Shell
stsadm -o execadmsvcjobs


Productive use for old SO-DIMMs?

Question: Being the local geek, friends and family turn to me for upgrading RAM in their computers. They provide the new sticks and I keep the old ones. As such, I have accumulated quite the collection of DDR3 SODIMMs, consisting of pairs of 1GB and 2GB sticks.
Over the years I've made fishing lures, tie clips and other "cute" things. Unfortunately I haven't found a motherboard with 16 SO-DIMM slots. I'm hoping for a productive use for these sticks. Something to benefit my 2008 Mac Pro or another device on my network.
Preferably the uses would be something other than vaporware products and something I might actually purchase, PCIe based or as a stand-alone thing.
Answer: You could sell them on eBay. Some people have 5 to 10 year old computers that take smaller RAM upgrades.

Productive use for old SO-DIMMs?


Origin of the term 'under influence'

Question: How did 'under influence', as in in driving under influence, get equated to 'intoxicated'?
Answer: "driving under the influence of alcohol" - avoids there having to be a definition of drunk and people being able to argue in court about how drunk they were.
Somebody once escaped because the police claimed he was drunk. They or their lawyer argued that the police weren't medically qualified to asses if somebody was drunk.
Nowadays in most countries there is a simple blood alcohol level at which you are guilty, and a machine to determine this - but lawyers like tradition
Answer: I'm from the UK, and for several decades we've had a specific law against driving with more than a specified concentration of alcohol in the blood. Depending on various factors, some people would be 'stinking drunk' just below that level, whereas others might be stone-cold sober just above it.
But before that the law, it was already illegal to drive while incapable through intoxication. The law wouldn't have specified which intoxicants, obviously. In common parlance it's just driving under the influence [of intoxicants].
I can't imagine US law would fail to address the same issues, so let's be clear that we're not just talking about alcohol here. I've no doubt there have been prosecutions in the UK of people people who drove while woozy from prescription painkillers. Cars are lethal weapons, and drivers have a legal responsibility to ensure they're fit to operate them (that includes wearing glasses if appropriate).
The shortened form Driving under influence, which I personally have never actually heard here in the UK, probably isn't because of any tendency for casual speech to drop insignificant words like 'the'. It's most likely just an over-literal expansion of the standard US police acronym DUI for the offense. Which sadly they still have to refer to practically every day.

Origin of the term 'under influence'


Compress video while keeping details

Question: I shoot POV bike videos using a GoPro Hero at 1280x720. Picture is fine (lots of details, fine color), but similar videos (also with GoPro or another helmet mounted camera, same resolution) in YouTube weigth just a 10% of mine, while looking gorgeous. Take a look at this RedBull example (83 MB) and then my last video (162 MB). RedBull look great at 16 MB/sec, while mine look not so good at 23 MB/sec (original size 480 MB). I'm using the same camera (or very similar), with no postprocessing. How can achieve a better looking video in YouTube? (BTW, I used kdenlive for editing).
Answer: While watching the examples it struck me that your video is stuttering as it is over the top with MBPS (23 MB per sec). So I would address your compression scheme first. I recommend that you consider rending your work in mp4 with 5 MB to 10 MB per sec. Here is the recommended video and audio compression as set by the folks at Vimeo for optimizing presentation on their site:
https://vimeo.com/help/compression
Another issue your video example is facing is that the GoPro does not have manual exposure controls. In your example, I see the bike going through bright areas and dark areas rapidly hence quick changes of exposure from the GoPro auto exposure. While the Red Bull example, shows the bikes in a stable light situation that does not force the GoPro to make wide adjustments. The solution to this problem is to either use a camera that offers manual exposure or shoot scenes that are evenly lit so they do not challenge the auto exposure to make big changes. Also, since the GoPro offers you at least a choice of Spot or Center Weighted auto exposure you might explore how one or the other might help expose the scenes more evenly.
Comment: Definitely agree - get the compression done *before* you send to YouTube.
Answer: YouTube will re-encode whatever you give it, and depending on the ratecontrol method YouTube uses, the complexity of the input can be a major factor in the file size of the videos YouTube re-encodes. Therefore, without altering your content, you may have little control of the size of the videos on YouTube's servers.
There is little need to adhere to specific bitrate suggestions: the best practice is to upload the best quality you practically can since YouTube (and others) are going to re-encode it anyway.

For Kdenlive specifically, I recommend a new export profile:
Open Kdenlive. Choose Render and then the Render Project tab. Click the Create New Profile icon. Fill out Profile name with H.264 Visually Lossless (video) / Vorbis (audio) or whatever you prefer. Extension is mkv. Parameters are:
f=matroska vcodec=libx264 -preset medium -crf 18 acodec=libvorbis aq=8 ac=2

For newer ffmpeg verions the parameter string is:
-f matroska -vcodec libx264 -preset medium -crf 18 -acodec libvorbis -aq 8 -ac 2

This should provide an output that is "visually lossless", yet it should be a manageable size for uploading. The audio format doesn't really matter as long as and Matroska and YouTube support it and you use a high enough quality (and assuming your ffmpeg supports the encoder). Others to consider are acodec=libmp3lame aq=1 or acodec=libfaac aq=100.
Who needs Premiere with such output flexibility?

Compress video while keeping details


On the guitar, if I play a song which is in the key of  D, where should I put the capo?

Question: How can I determine where to position a capo based on the key of the music I am playing? I current can only play songs in the key of C with no capo. Is there any rule to follow?
Comment: Please understand that using a capo is optional. Many guitarists never use a capo. It is possible to play in the key of C or D without using a capo; you just need to learn what to do with your fingers!
Answer: If you are currently playing it in the key of C and want to use the same finger shapes for D just pop the capo on your 2nd fret. This shifts everything up 2 semitones, ie. from C to D.
But as Wheat mentioned in his comment, if you learn different finger shapes, you can play in any key without using a capo. Most users of capos use them either for ease (if there is a tricky chord that just works better in a particular shape) or for a particular sound (letting open strings ring is very different to playing barre chords higher up the fretboard)
Comment: In this case, yes, capo on 2nd fret. But while it is true that you can play in all keys without the capo, you may want to have the right open strings ringing, which is what the capo is there for.
Answer: To elaborate further what Wheat and Dr. Mayhem mean about playing without the capotasto [yes, I had to look it up].
You can transpose the chords in your head, from C to D, by shifting each chord up a whole step. So when you read C, play D. When you read D, play E. When you read Am, play Bm. Etc.
Playing with all barre-chords can be a useful intermediate step. As is Nashville notation. [Actually, I really mean Roman-numeral notation. I've learned that 'Nashville' uses arabic numerals, which are often already covering the page! The point is notating chords by their function in the scale. Then you can apply the pattern to any scale.] These techniques focus attention on the internal structure of the song, rather than its external location on the Concert C scale.
Edit: Re-reading the question, I'm now a little confused. So here's some hemming and hawing to cover all the bases. :)
If the song is simply written in D, then you don't have to do anything (nor need you use a capotasto) to play it. It just means that F and C are sharp, so D major and A major are possible instead of D minor and A minor like you have in the key of C. Chord symbols should already account for this and give you the character (Major/minor) and any accidentals on the root (C♯° & F♯m are two chords from the harmonized D Major scale). Music written in staff notation should remind you of the key at the start of each line, just after the clef.
If the song is, somehow, written for an instrument in the Key of D, then you can capo at the second fret to perform the key correction. This is essentially what a B♭ horn player must do mentally to read "C" music.
In general, for music written for an instrument in the key of X (B♭, E♭, whatever), the key note X is written as C on the page. Note you can also de-tune the strings to perform a key correction in the reverse direction; a guitar de-tuned a whole step can read B♭ horn charts with ease (very useful in pep-bands and concert bands where your "closest" choice might be marimba, but the marimba part doesn't have enough info (and the bassist won't share); in these situations, the horn-parts will show you the harmony, the backing riffs, and the melody, but you have to correct the key).
Comment: +1 for the last paragraph on music written for an instrument in key of D. Note that D natural in a sheet music transposed for an instrument in the key of D, is noted as if was a C to make it easier to read playing the D-instrument.
Answer: To play in the key of D with the 'C shape,' you'd want to capo your guitar on the second fret. Each fret represents a half step and there are two half steps from C to D (so if you capoed on the first fret you'd be playing in C# with the 'C shape').
The reason I use the term 'C shape' is because I learned very early in my playing about the CAGED method which helped me learn all about what you are somewhat referring to. The chords C, A, G, E and D are the five basic shapes played with open strings meaning those can be moved all around the guitar. Think about a basic B chord. That chord is actually just an A chord moved up two frets (with your first finger acting where the open notes were). If you play a D up four frets then you will be playing an F# (D#-E-F-F#).
So you could play a song in the key of D with the capo on the fifth fret if you played with the open A shape. On the second fret with the open C shape. On the seventh fret with the open G shape, etc.
Google the 'CAGED method' and it will help immensely in your understanding.
Answer: Even though this is a guitar question, the easiest way to think about this is to visualise a piano keyboard.

Going up one fret on your guitar, is equivalent to going up one key on the piano - including the black keys.
So when you finger the first fret of the E string, you are playing an F. When you finger the second fret of the E string, you are playing an F#.
A capo has the same effect as a finger. So if you put a capo on the second fret, you change your "open" strings from E,B,G,D,A,E to F#,C#,A,E,B,F# -- prove it to yourself by finding the notes on the piano image and counting two semitones up.
The same principle works with chords. Since you play your chord shapes moved up the neck the same number of frets as the capo position, the whole chord is transposed. So if you play an E major shape with a capo on the 2nd fret, it's an F# major.
So, to answer your question directly: let's say you want to play a tune in G major, but you want to use C major shapes. How many frets up is G from C? Start at C on the piano keyboard, and count one-key steps until you reach G. C#,D,D#,E,F,F#,G -- 7 steps, so put your capo on the 7th fret.
The same reasoning will apply when you advance to barre chords (which you should do as soon as possible). Since you are fingering every string, barre chords are movable. If you move a barred F up 4 frets, you can see from the piano picture, that you'll be playing an A. One way to think of a capo is as a static index finger for barre chords.
Some people can be a bit snobby about capos, because it can be a cop-out alternative to learning a full complement of chord shapes. But there are worthwhile reasons to use a capo; it lets you play different chord inversions over a song in a particular key. I particularly like to to capo my 7th fret when playing alongside another guitarist who's playing chords without a capo. It prevents the two instruments competing for the same range, and my acoustic has a sweet sound in that register.
One final note -- you are asking how to play a song in D, using C shapes. The standard chord shapes for D, G, A are much easier than those for C, F, G -- so a capo might not be your best option in this case.
Comment: I want to emphasize the last paragraph about D, G, A are much simpler chords on the guitar. If using barre, the best "ground set" of chords are E, A, B (where B is just A using barre at 2nd fret). Then all other keys are just moving using E and A with barre at the relative fret position based on E as ground key.


What is the difference of FreeBSD and Linux?

Question: I give you a basic question. Because I 'm a beginner.
I want to build a server with Web application.
I am troubled whether I choose FreeBSD or Linux
What is the difference of FreeBSD and Linux?
Please gime me  recommended criteria for OS selection.
Answer: FreeBSD is decended from the BSD line.  It is based on a 100% re-write of AT&T's original.  Although it initially had legal issues with AT&T that hampered its expansion, it was eventually cleared (when it was discovered that AT&T had appropriated BSD code, the tables turned).  As a result, it is 100% free and clear of any known legal claims against it.  It is licensed under the "BSD license", which is very liberal and allows for redistribution for profit.
Linux is a 100% from-scratch System V look-alike.  It was started by a Finnish programmer who gathered several other people together.  Over time, the "linux kernel" grew in developers and lines-of-code, adding new features along the way.  It too has had its share of legal issues, instigated by the SCO Group, who tried to claim ownership of some of the kernel code.  To date, no infringing code has been found, and there have been speculative ties between SCO's actions and a large lump sum of money that Microsoft "gave" to them.  It was controvercial at the time because Linux uses a GPL Version 2 license, which requires that any programs released to the public must also (a) have the source code readily available, (b) must be available under the same license, and (c) must have a notice attributing the original author.
Both systems are fairly stable.  Both have long development histories.  Both have active development communities and are not likely to go away anytime soon.
In terms of server network support, the historical consensus is typically on the side of the BSDs, which have been demonstrated to accommodate heavy connections and loads.  In terms of ubiquity, Linux is found in the most surprising places, and has a thriving software culture.
To answer your question about web server applications, I would probably favor BSD.  The basis of the selection is that BSD's network stack has been demonstrated (historically) to have a slight edge against Linux.  For back-end deployment, the flexibility and ubiquity of Linux distributions means that I would have a large array of software available to me.  Yes, to those BSD lovers out there, I am aware of the breadth of software available through the BSD ports program.
However, it is far easier to find Linux administrators, a potential factor that affects deployment.  If this is a rapidly changing or growing installation, finding BSD talent might lead to a labor issue in your deployment.
So - it depends. :)  Are you going to need full-time staffers?  Stick with Linux.  Are you looking for large site deployment on smaller hardware?  BSD might work for you.
Comment: IMHO it really doesn't matter which you choose.  Although there are differences, switching from one *nix variant to another is a minor matter filled more with annoyances than with unsurmountable problems.  So, pick one, understand it as completely as you can.  There is not a "correct" answer here.
Comment: Although correct i general, there are two factual errors here. First, not only the BSD license allows redistribution for profit, the GPL (and many other F/OSS licenses). What the BSD license allows that the GPL does not is closed source redistribution.

Also, to my knowledge (and I couldn't find anything on Wikipedia to say otherwise), the GPL does not require you to any send changes back to the original author.
Comment: Very informative.  I think in the end of the day you need to choose whichever one you feel most comftorable with and which ever one you think you can support the best.  I come from BSD so I am biased towards it, however have supported Fedora and a couple others and find both have there positives.
Comment: @Mikael Auno, noted, fixed.
Answer: For a webserver I would choose linux. Distributions like Debian and Ubuntu are supported and security-patched for a really long time. (the ubuntu versions with long time support anyway)
For servers I think this is important. I have a FreeBSD 6.1 server that I can't upgrade, because 6.1 is just gone from all FTP servers and no fixes are made for it. It's not that old, but considered obsolete and I really fear upgrading it. Especially remote upgrades.
On the other hand I have a Debian Linux server that I've been running constantly since 1999, and have kept it updated and patched easily. All remote. Last time I saw it was 5 years ago when I wanted to check if the CPU fan was still working (it wasn't, I changed it).
For servers that will just have to work, debian is easy to keep updated and there is no problem with upgrading from one release to the next, even remote.
The Debian (and Ubuntu) packaging system (apt-get) make it so much better for servers than anything else that it's not even funny.
Debian GNU/kFreeBSD seems nice. I've played with it a bit, but not run it in production.
Comment: "I really fear upgrading" <-- What a terrible reason leave a system unpatched. Find a competient FreeBSD admin, it's really not that hard and very likely that you wont need to mess with the application software. Also, FreeBSD has extended service releases, use one of them if you want patches long into the future.
Comment: I did find "competient" FreeBSD admins, one of whom makes it a point to go to international conferences on "package management in BSD". They sort of bowed their heads in shame that there was at least at the time no solution to "upgrading" that actually worked.
Answer: There are lots of "under the hood" differences between the two, and indeed between different Linux versions. Somehow I don't think that's what you're actually asking about.
From the practical point of view of running a web server for me it comes down to just two things:
1) Can you secure it
2) Does it have good package management
I used to run my personal web server as FreeBSD - it's package management was a giant pain the backside compared to something like Debian or CentOS Linux. Personally, I won't use anything that doesn't have a good binary package manager like apt on Debian-based distros or yum on RedHat-based distros like CentOS.
As for security, SELinux is pretty nice to have, and both FreeBSD and Linux have good firewalls, so perhaps there's not much difference there.
Bottom line - I've admined both Linux and FreeBSD web servers, and I had far less trouble and far less work with the Linux ones. They're just easier to look after in my experience.
Comment: FreeBSD's package system is quite good, you were probably using the Port system, which is something different. Lack of understanding doesn't imply a technical shortcoming.
Answer: The last I checked, Linux does better on multi-core systems. So if your application server has many CPU cores, Linux may be a better choice.
I also think that Java support is a little better on Linux so if you need Sun's or IBM's JRE, that might be a consideration. I believe that the free ones like IceTea work just fine on BSD.
Answer: You need to focus in on the Linux side and select a distribution, and decide what type of packaging system you want, what type of security updates are there, hardware support etc etc.
Then you can ask how does Debian stable or Ubuntu Server compare with FreeBSD.
And at the end of the day they will come in very close and FreeBSD will be better on some things and Debian will be better with others things.
It is a tricky question.
Answer: FreeBSD and Linux really differ only in one - development process. FreeBSD being a bit more consistent and stable, while Linux's strength is in versatility, neat features and a lot more people developing and using it. That's why it's easier to find documentation/help if you use Linux, especially if you use popular distribution like Debian/Gentoo/RHEL/CentOS/etc.
P.S. Some people say you should choose OS that your friends/coworkers are familiar with.
Answer: Development process with FreeBSD is more consistent
Here you can see the source of every release going back 17 years and its under source control.
http://svnweb.freebsd.org/base/release/
Documentation is important, i doubt there is anything as complete in the Linux/GNU world.
http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/
Comment: Whilst this may theoretically answer the question, [it would be preferable](http://meta.stackexchange.com/q/8259) to include the essential parts of the answer here, and provide the link for reference.


Emailing all site users

Question: I'm going to be emailing all of my site users to update them on recent developments and remind them to come back to the site.  Are there any special precautions I should take.  I was going to do this through a loop in PHP.  I have about 1,000 users.
Answer: Generally you'll want to avoid being detected as SPAM through using the right content and DNS records.
Sending 10 or more similar emails to a domain in a 30 minute window has also caused us some issues in the past (do not know the cause and it only affects a few domains). So we tend to make batches (in a scripting language such as PHP) then send through a script either using cron or at.
Limit the number of emails sent in each batch and monitor for rejections and abuse@/spam@ replies. Using receipts and unique tracking images will also help you determine the number of emails received. Unfortunately there is no one-size-fits-all solution when it comes to the sending side, but by being proactive you'll find the gaps that need plugged.
Answer: One thing you will want to do is make sure to add an unsubscribe at the bottom of your mass email.  That way if any of your site users do not want to receive emails like this one in the future, they have a way to do it.  This is just good practice in general.
In general it is ok to have mailing lists for different kinds of email for your site so if yous end a different kind of email in the future site users would have to unsubscribe from that separately but your really have to give them a way to get out this kind of email in the future.
Answer: My advice:

Read the other answers here
Realize that sending email to 1,000 users entails a high degree of risk that your users won't get the email because it's classified as spam, that you'll be classified as a spammer, or both
Consider spending money for this rather than doing it yourself.

Companies that do this for a living know how to get on whitelists for major email providers (hotmail, gmail, aol, etc) and will help you with deliverability, unsubscribe links, etc.
Some options are discussed in this question on the webapps site. With mailchimp or campaignmonitor, sending to 1,000 users can cost as little as $15.
Answer: When sending e-mail, its generally good to only send to people who have opted in. During your registration process, you should have a check box similar to this:

[ ] Keep me up to date with what goes
  on here (approximately n emails
  monthly)

Then, e-mail only users who have opted in. A much stronger strategy is to use what is known as a double opt in, which requires the user not only to click the box, but also click a confirmation link via e-mail before placed on the list to be contacted. Of course, as @Random Ben suggested, always provide a simple, one click means for users to unsubscribe.
Depending on your country and local laws, you may also be required to:

List your full business name, address and telephone number
Inform the user that they are in no way obligated to take action on the e-mail
Clearly state that the e-mail is not an invoice of any kind
Other requirements

I would not send a thousand e-mails in a single loop. This could set off anti SPAM measures from your host, as well as ensure your mail is rejected by remote recipients such as MSN. If revenue permits, perhaps check into using a third party that specializes in bulk mail delivery. They will know all of the laws you need to follow, they will have sophisticated software that helps to guarantee a low bounce rate and they are usually quite cheap.
Otherwise, take a look at some of the open source mailing list / bulk mail managers on sites like Sourceforge. These may not be as sophisticated as commercial solutions, but most of them do a good job at 'trickling' out the messages over a longer period of time, while making sure that you don't send too many to one host at one time.
For instance, if 700 of your visitors used hotmail.com, and you did not take special care, most (or all) of your messages would end up in SPAM folders, or not delivered at all.
When (and yes, it is when, not if) you end up having to deal with a SPAM blacklist, you will  always have a much easier time if you can prove that you use a double opt in system. This tells them that whoever complained (probably) just forgot that they subscribed.
I'd spend just as much time worrying about how people get on the list to be contacted as I would worrying how to send the e-mail.

Emailing all site users


How to create a color tinted black and white effect?

Question: I was wondering how I would go about recreating this look on a photo using Photoshop?
Comment: **step 1:** greyscale  **step 2:** colorize
Answer: The easiest way to create an effect like that with precise control is using a Gradient Map.
Start with a normal colour image.

If you apply a Gradient Map Adjustment Layer on top, with a pink to black gradient, the effect will be identical to what you're after. It even means you can choose precise colours for anywhere along the tonal range. I'm a big fan of Gradient Maps.

Pros

Precise
Quick
Editable afterwards
Can be saved as a gradient and applied to other documents quickly

Cons

None :)
Answer: Since the text in the cropped image implies this was part of a larger design, it is possible that a layout program was used. As an alternative to colorizing the image in Photoshop (which is the question as asked), I would typically do this using a greyscale image (not "color" nor "RGB" nor "CMYK"). After placing it in the layout, one can then select a background color for the image using the color swatches.
This makes it easy to adjust the color based upon the document specification and use a single image with multiple colors (such as different colored chapter header decoration etc).
Note that the foreground color can also be adjusted independently with this method, but one typically needs to have the "content tool" selected (rather than the "box/window tool")
Answer: There are many ways. An easy one is to put the photo on one layer, desaturate it to make it black and white, then create a new layer above. Fill that layer with fuchsia and set it's blending mode to 'multiply'.
Answer: There are many methods, but I would change the photo to greyscale first using the (Image>Adjustments>Black and white) filter. Then, open (Image>Adjustments>Photo filter) and change the adjusting color to the color and intensity that you desire.
Answer: The easiest way is to convert the image to a duotone color mode.
If you're starting with a CMYK or RGB image, you'll first need to convert it to grayscale (discard color information).
Then choose Image > Mode > Duotone.  Now choose one of the magenta presets in the duotone options dropdown.
Save and done!


API V2 Private Beta Begins

Question: It's about time this thing got under way.  If you're participating in the private beta, you should receive an email to that effect.
If you were also a member of the V1.0 private beta, you'll notice we're doing things a little differently this time.  There isn't a separate site for discussion, and we're not locking down access to the documentation.
All questions and bug reports (with one caveat, detailed below) should go on Stack Apps with the api-v2-beta tag.  We'll be closing (and subsequently deleting) these posts as they're dealt with.  You should not expect any posts created with the api-v2-beta tag to survive the beta.
The one caveat to bug reports: if you find what you believe is a privacy violating bug (these presumably have to deal with access_tokens), please report it to email@example.com.
Broadly speaking, the API should be functionally correct.  Methods should return the data you expect in the manner you expect it (compression, encodings, etc., should all be correct).  Naturally, the point of a beta is to find those cases where this is not true; if you come across any, please post them with the bug tag.
Towards the end of the API private beta, it will probably be necessary (depending on the changes that occurred during the beta) to regenerate filters.  Instructions on how to do this (as well as whether it's necessary) will be sent out when the time comes.  It would be in your best interest to make it easy to swap out filters accordingly (this is generally true, independent of the beta environment).
Answer: I almost forgot:
Thank you!
We have been looking forward to this for a long time and it's great to finally get a chance to play around with the new API.

API V2 Private Beta Begins


What does "statistically unchanged" mean?

Question:
The universe continually expanded but remained statistically unchanged as new matter is constantly created.

What is the statistically unchanged? Could you give me an example?
Answer: That would be referring to the average density of the universe. If space is expanding in a measurable manner (that is, if expansion is such that localised clusters of mass, such as an observer can detect the change[1]), then the statement asserts that matter is being created in the "new space" at a rate sufficient to maintain the average density of matter in the universe. It's that average, or statistical mean density that is being referred to in the your example sentence.
[1] If all space were expanding at the same rate, including the space between particle probability waves and their wavelengths, then the observer would be expanding at the same rate as the universe, as would any measurement references, so the expansion would be unmeasurable.
Comment: It may worth pointing out to readers that the quotation comes from Fred Hoyle, who was providing (in 1948?) a possible explanation of how a Steady State theory might be consistent with earlier observations of an expanding universe.
Answer: I think the author may be using the phrase in a slightly unscientific/unorthodox way.
Usually, following an apparent change, something remains "statistically unchanged" if the change is not statistically significant. If you measure something, there will usually be some degree of change that indicates that the phenomenon you are measuring has "really" changed due to some factor/influence, and smaller changes in the measurement which are just down to "random" fluctuation or measurement errors and which you'd expect to get by pure chance on repeatd measures even if nothing has really changed the thing you're measuring. There are statistical tests to determine the probability of an observed change in a measurement actually reflecting a "real" change in the observed variable.
I can't exactly reconcile this with the example sentence you gave-- I think they could be misusing the term slightly-- but usually, "statistically unchanged" would imply "may have changed in terms of the raw measurement, but this change does not pass the relevant test(s) for statistical significance".
Comment: As Henry noted in his comment to Stan's answer, the author was being rigorous and precise about a theory that had been widely accepted but was about to get thrown out on account of new evidence. He meant that the statistical properties of the universe (mass density, ...) would remain unchanged.


How do we teach a pre-schooler about money and shopping?

Question: When I go to a store with my four year old son he wants to buy a lot of stuff he sees. Also he constantly claims that he needs a new toy. How do I explain to him that we can't buy everything we want?
Comment: http://www.thesimpledollar.com is a great blog about personal finance that also addresses this in several articles. I'm not affiliated, just a fan.
Comment: Sounds like a good time to introduce an allowance.
Answer: Time to buy a money box/'piggy bank'
We bought our son a Thomas the Tank Engine money box and we often randomly give him the small change from local shopping trips. He enjoys putting the coins into his money box and pretending to count the money occassionally.
Now, when we go shopping and he latches onto something he likes the look of, we simply ask "okay, you can buy it if you want. Did you bring your money?". Of course, he didn't, so he then realises he cannot buy it.
This only works if we stand firm on this position - if you 'loan' them the money even just once, you're back to where you started.
Update
He's 2 years older now and so can count the money and read the prices in the shops. We got him a really small purse into which he can put some of his pennies so that he does have some money with him. This enabled him to purchase some small items like stickers and an old toy from a charity shop. He takes great care of the old toy, since he bought it with 'his money'.
Answer: I suggest a simple habit. Never buy toys on impulse; no matter how difficult the merchandizers make it for us. (Toys in the check out lane, really?)
Each time explain that the child can think about getting the toy and give reasons on the following day. Let them know that if you approve of the reasons, on the next trip to the store you will get the toy if they remind you.
All of the above hinging on their ability to hold the desire for the toy over time.
Remember to demonstrate this in your own behavior.
This is primarily for combating impulse buys. Budgeting and scarcity will necessarily be handled differently. But if you are not truly in a financial bind, avoid making your child feel an imagined/false financial insecurity. They don't need that added stress.
Comment: An excellent approach! I wish I could +2. And very useful for adults, too...
Comment: This is the closest to what I can live with...
Comment: Great Plan!  Additionally, the difference between need and want takes time with toddlers so reiterating, "I know you want this toy" when he saids he needs it "but you don't really NEED it like you need food or water" will help to begin cementing this vocabulary.
Answer: I'm facing the same problem and there's a hidden problem here that lurks hidden in the dark: Constant want and depression. A child that will get everything he/she wants will become a depressed child. I see it with mine. I don't know any other 8 year old who has the following (for the asking): XBOX 360 with Kinect, newest iPod Touch, iPad, his own computer with internet connection, Nintendo 3DS and toys beyond his capacity to enjoy. Do you think he's happy? no. He wants new things all the time - has no appreciation for what he has. Every trip outside the house must result in a "toy" or purchase. It's no even things he wants - if he can't find things he wants on the shelves, he'll pick something he doesn't want just for the "rat-rush" of the buy and he'll lose interest within minutes and become depressed again.
I realize it's our fault for pampering him, but if there's anything we learned from this - buying a kid whatever he wants whenever he wants it - is child abuse. It's harmful, it will depress him/her and seriously hurt the child.
Avoid it at all costs. Buy him something for his birthday he'll appreciate. Never make it a weekly/bi-weekly ritual.
Comment: +1 for a very real "worst case scenario". It must be hard to back out of that situation.
Comment: What a nice admission too!  Thanks for the helpful and thoughtful warning.
Answer: Our twins just turned 5.  Here are some things that worked for us. Pardon the long list, our twins have very different temperaments and we've found that very different things work for each of them:  One responds better to talking, and the other needs consequences before the talking sinks in.  I'm also giving our tactics for dealing with the rudeness that I find most aggravating about kids who frequently want things in public.  I don't know if you have this problem, but they've always gone hand-in-hand for us.
We talk about how Mommy leaves for work each day (Dad is a SAHD) to work and earn money, and how Mommy has to spend more time working if we spend more money.  This isn't just one conversation, it's something we discuss when the kids ask things like "Why does Mommy leave the house each day?" and "Why can't we afford that?"  This helps the kids see that buying more is a lifestyle choice, and that our family values time together over getting more stuff.
Sometimes, we give the children most of the "fruits and veggies" portion of our grocery budget and let them pick out their own produce, up to the budgeted amount (usually $5 each).  They get a feel for how money works, and they love eating the (healthy!) food they picked out.
After thanking God for giving us food at meals, we thank Daddy for preparing the food (I lead this), and my husband has started leading the kids in thanking me for earning the money to buy the food (and sometimes he and the kids start listing out other things we buy with my income - water, electricity, our house, etc.).  This helps our children connect money with work and with the things we truly need, like food and shelter.
We play the "gratitude game", where people list things they are grateful for - toys, family, nature, our home, etc.  The kids get pretty into thinking up detailed things they appreciate.  This lets us discuss gratitude for what we already have in our responses to why we aren't buying more.  Gratitude is a very abstract concept, but teaching it by giving examples of things we are grateful for has worked well.
When we are asked rudely in the store to buy something, I talk about how I am sorry, but she asked rudely and I don't buy toys for rude children or selfish children.  Then I focus on the manners, explaining what a polite way to deal with the situation would be.  I then refuse to buy the toy even if she asks politely because she started with rudeness, and sadly explain that she has to be polite from the beginning.  A bad reaction to this information (throwing a fit, for example; or, continuing to be rude) leads to more severe discipline.
Nagging, repetitive questions (or statements!) that we've already responded to are a form of rudeness, and disciplined accordingly.  The word, "Why?" is not considered a complete question, and we coach our daughters on asking the full question before we answer, e.g., "Why can't we buy that toy?"  "Why does it cost too much?"  "Why can't we afford it?"  "Why was I [the child] too rude?"
We keep a "To Buy" list of things we want, and when our kids want something and ask politely (on the FIRST try!), we tell them we'll put it on the list and think about it.  Sometimes they get these items for holidays or when they've been especially well behaved.  Very rarely, they will receive a politely requested item that we can afford immediately, or they will be so well behaved when we say "No" that we will change our minds and get it for them then, saying that we are celebrating our joy at having such a polite child(ren).
Answer: Here are some things we do with our 4 year old:
If we are shopping with my son and he is going to get something we ask him to take the item and the money to the teller / cashier himself. In this way he can see how the transaction involves money being spent and it doesn't come back.
The same as Ethel mentions in her answer, we explain that money is earned through his parents going to work. We also explain that we are given a limited amount of money for our work.
Whenever we need to pay for something expensive we also mention to our son that what we are paying for is expensive e.g. if we need to pay our electricity online. We do this without trying to be negative, it's not to make him feel guilt, but to get an understanding that some things require more money than others.
I also explain to him when we are shopping that we can't waste money by buying lots of special things at once (we can't have a shopping trolley full of chocolate and ice cream) because money is valuable and can't be squandered.
Children can understand complex ideas by piecing together little pieces of information. So it's not about trying to explain hundreds of details, but planting lots of little ideas.
Comment: Good points. I love the idea of letting him pay himself!
Answer: The desire of the human flesh is what we all need to learn to overcome. Your child doesn't understand math and doesn't understand where the money comes from either. So he's not going to understand the value that money represents.
The value that your child needs to understand, is the value of patience. You can start teaching them this at home. Here's what you do.
Before dinner, yes..  before dinner, offer your child a cookie. But tell them, that if they wait until after dinner, then they can have two cookies.
Of course they're going to want the cookie now. You have to do everything you can to convince them to wait until after dinner. But don't force them. If they want the cookie now, and it becomes a heated debate, then give him the cookie.
Keep doing this at dinner time until you can convince your son to wait until after dinner. Once your child realizes that they can get two cookies if they wait, then mix it up a little and offer them other kinds of treats in the same manor.
Of course as your child gets older you can come up with all kinds of new ways of doing this. What you're going to notice is that when you're at the store your child will be much more patient with you when you tell them that you cannot buy them something right now. And when you do finally buy something for them, remind them that because they waited they can pick out a toy.
God Bless!
Comment: You'd be surprised actually. Our 3 year old seems to be on an attention crave because he's no longer the youngest. However, despite his unwillingness to calm down, he still understands the concept very well.

By no means is it at all cruel. It's a decision that you're teaching your child to make. Its a practice that will serve them well as they get older too. This basically replicates earning interest on your money, a valuable patience skill to have.
Comment: This sounds almost cruel, although very good teaching effect on delayed gratification when it works. Would it backfire if you can't convince the child to wait until after dinner? I guess the child has to be mentally mature enough to consciously control himself that much - I know it would be a disaster to try with my toddler at the moment :-)
Answer: What we did successfully with my kids from 4 (from 3 with the youngest) was to let them know that they could spend their weekly allowance (at that age 20 pence) and earned pocket money on something 20p or less, or save it to get something bigger that they want.
Our youngest is now 5 and she is perfectly capable of saving her 50p a week for a few months to get something more expensive, and the eldest, now 10 has managed to save £60 to hire quad bikes, segways and karts for a weekend sporting event.
They earn more for chores, such as helping me clean the car or tidying their rooms - and they have learned the value of money. If they want something bigger they can carry out more chores, trade with their siblings or save for longer. A valuable life lesson!


How to send multiple MVP matrices to a vertex shader in OpenGL ES 2.0

Question: I'm working my way through optimizing the rendering of sprites in a 2D game using OpenGL ES and I've hit the limit of my knowledge when it comes to GLSL and vertex shaders.
I have two large float buffers containing my vertex coordinates and texture coordinates (eventually this will be one buffer) for multiple sprites in order to perform a single glDrawArrays call.  This works but I've hit a snag when it comes to passing the transformation matrix into the vertex shader.
My shader code is:
uniform mat4 u_MVPMatrix;
attribute vec4 a_Position;
attribute vec2 a_TexCoordinate;
varying vec2 v_TexCoordinate;

void main()
{
    v_TexCoordinate = a_TexCoordinate;
    gl_Position = u_MVPMatrix * a_Position;
}

In Java (Android) I am using a FloatBuffer to store the vertex/texture data and this is provided to the shader like so:
mGlEs20.glVertexAttribPointer(mVertexHandle, Globals.GL_POSITION_VERTEX_COUNT, GLES20.GL_FLOAT, false, 0, mVertexCoordinates);
mGlEs20.glVertexAttribPointer(mTextureCoordinateHandle, Globals.GL_TEXTURE_VERTEX_COUNT, GLES20.GL_FLOAT, false, 0, mTextureCoordinates);

(The Globals.GL_POSITION_VERTEX_COUNT etc are just integers with the value of 2 right now)
And I'm passing the MVP (Model/View/Projection) matrix buffer like this:
GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mModelCoordinates);

(mModelCoordinates is a FloatBuffer containing 16-float sequences representing the MVP matrix for each sprite)
This renders my scene but all the sprites share the same transformation, so it's obviously only picking the first 16 elements from the buffer which makes sense since I am passing in "1" as the second parameter.  The documentation for this method says:

"This should be 1 if the targeted uniform variable is not an array of matrices, and 1 or more if it is an array of matrices."

So I tried modifying the shader with a fixed size array large enough to accomodate most of my scenarios:
uniform mat4 u_MVPMatrix[1000];

But this lead to an error in the shader:

cannot convert from 'uniform array of 4X4 matrix of float' to 'Position 4-component vector of float'

This just seems wrong anyway as it's not clear to me how the shader would know when to transition to the next matrix anyway.
Anyone have an idea how I can get my shader to pick up a different MVP matrix (i.e. the NEXT 16 floats) from my MVP buffer for every 4 vertices it encounters?  (I am using GL_TRIANGLE_STRIP so each sprite has 4 vertices).
Thanks!
Answer: How many sprites are you rendering at once? Are you using a sprite atlas? Generally speaking, setting the transform matrix and drawing the sprite one at a time is the cleanest way to do this. If that is causing significant slow down, you are drawing a lot of sprites.
Normally, I would recommend a Uniform Buffer Object for your situation, but I cannot find any documentation suggesting OpenGL ES supports it.
What is the nature of the transforms? You might be able to infer the matrices using other data. Doing simple translation, for example, could be passed in with the sprite vertex data.


Can I shop an unfinished novel?

Question: I've  been writing a novel that addresses some very current themes. My belief is that if I can get it out there quickly, it will succeed well. I'm working on it frantically, but will agents consider representing a work in progress?  At what point is it close enough?
Comment: These are great answers for unpublished writers, thank you. (In my particular case, I am an established author, albeit of nonfiction. I probably will contact my agency's fiction agents. I was hoping to get an idea of at what point I should do that.)
Comment: just a note that in the future if you would so desire you can edit your question to add additional information rather than leaving a comment (which, if there are a lot of comments added, means it could get lost in the shuffle).  You should see an edit link under your question's tags.
Answer: Unless you are already an established name in the industry and one known for timeliness and reliability, you will have a hard time shopping around an unfinished book. There are a tremendous amount of finished manuscripts piling up on agents and editors doorsteps already.
But keep in mind, the publishing industry is a slow moving machine in general. Consider how many years these vampire and zombie trends have lasted. My advice would be to finish your book.
Comment: How did you know it was about zombie vampires? ;)
Comment: I'd like to see one about vampire zombies, just to be different.
Answer: It's true.  It should be completed, polished, and ready to go.
This is because:
A) it's nearly impossible for you, a first-time novelist, to know how much more time you need until you've got the project as good as it can be.  Writing a book to a publishable level is a lot more than just finishing the first draft.  Before you submit your work to an agent or publisher, you should have written the first draft; polished it through as many subsequent drafts as are needed to make it as good as you can make it; found good beta readers to go through it and give their feedback (and this takes time, and it's really not right to rush people who are doing you a pretty huge favour); made whatever revisions are necessary based on their feedback; and then, ideally, pulled your attention away from the book for a while so you can come back to it with fresh eyes and give it another thorough reading/revising.  Until you've done all this several times, it's going to be really difficult to be sure how long it will all take.
B) it sounds cheesy, but you really do have only one chance to make a first impression.  There are some agents and publishers who will accept a resubmission if the work has been substantially revised, but for many of them, it's a one-shot opportunity.  You will, I assume, want to start with your 'top' candidates first.  If you send them work that isn't totally polished, you'll be ruining your chance to work with them.  And while many agents and publishers are slow to respond to queries, others are quite speedy (I was just reading about two-minute turn-arounds for some agents asking for partials), and you don't want to ruin the relationship with them by having to confess that you're not quite done with the product you've just tried to sell them.
C) There are a lot of flakes out there, trying to get published, and sorting through them is a big job for publishers and agents.  You need to do whatever you can to set yourself apart from these people, and querying an unfinished MS will move you in the wrong direction.
I absolutely appreciate the impatience you're probably feeling.  One of the hardest things about novel writing is the long, lonely time you have to go through before getting any feedback or reward for your hard work.  But I don't think early submissions are the answer.  Join a writing group, and share your MS with them.  Post a chapter on-line, and look for feedback in the comments.  Read it to your dog, if that helps.
Answer: No you can't shop an unfinished novel. Almost everyone has good ideas- for movies, books, businesses, but very few have the discipline to stick to their idea and produce something useful. Many get bored and stop half way.
In books, very few people even finish the 1st draft. Those who do, never get around to revising it and producing something professional. Of those who do, very few seek feedback to see if their work is even interesting. You can see that if you are trying to sell something that hasn't even been finished yet, the odds are stacked against you. The publishers/agents know this, so why should they waste their time on you?
Just having a great idea or even a rough draft of a book isn't good enough. To produce something of beauty, something people appreciate and are willing to pay for, requires hard work and discipline. To misquote Samuel Goldwyn:
"A good book idea isn't worth the paper it is written on" :)
Answer: If you rush your novel, it will be crap. You're better off taking you time and making sure you do everything correctly. You can't just pump out a first draft and send it off to publishers. They'll laugh at you. Instead take your time; publishers will still be there when you finish the book.
Only established authors can shop unfinished manuscripts. Publishers aren't going to take a chance on a novel that's not finished by an unknown author. There are thousands of finished manuscripts being shopped around at any given time. Why should a publisher take a chance on a novel that may never get finished, or once it does, might suck, when they have tons of complete choices to pick from?
Answer: Anyone can "shop" a story/novel/script at any time. The challenge is to be successful.
Unless you have a track record or a recommendation from a close friend your chances of getting in to see an agent much less an editor are probably close to surviving an asteroid hit ten feet in front of your car.
Jerzy Kosinski (award winning Polish American author) tried to get a novel published (it already was) by sending it out as if it was a NEW work. He received MANY rejection letters. That was years ago when it was easier.
Today the slush pile is bigger, the publishers trying to make money against technology, and a fickle audience.
I doubt that you will succeed at anything except becoming frustrated.

Can I shop an unfinished novel?


Alternative to the 1-2-3 rule needed

Question: I have a 1,6 year old son. Today I first put him in "the corner" after counting to three, explaining that this would happen when he doesn´t behave. Then I told him that he should stay there until he was ready to apologise. (He didn´t close the toilet when asked.) He cried and I know that he didn´t understand but I still feel its time to show him somehow that I mean business when no means no. My husband is a programmer and is afraid that our son will hate numbers if we use 1-2-3 as the trigger to "the corner". And we want our son to love numbers. So I need help... what can I use as a definite "Oh no you didn´t" type of phrasing that makes him realize that punishment is on way. This has to give him time to stop...1-2...
Thank you for your world of wisdom.
Comment: "My husband is a programmer and is afraid that our son will hate numbers if we use 1-2-3" = I don't think that will cause him to grow up with a hatred of numbers. ;)
Comment: @DA01: No, but it might if they started counting in binary. *rimshot*
Comment: He could turn into the child who gets upset at being sent to the corner at 1 because he thought it was a zero based countdown.
Comment: I use "knock it off" then I mute the cartoons or something and they straighten up. I've never really had to do time outs or the 1-2-3 thing. Knock it off always seems to suffice
Answer: We use the 1.2.3 rule, and I'm a computer programmer, and my oldest son (6 years old) loves math. Just because you use numbers, it doesn't mean they will relate that to math. My now-1st grader loves addition, subtraction, even does simple (6x3 type) multiplication. We have, however, used 1..2..3 since he was little to let him understand that we need his attention NOW. Now my 3 year old doesn't get the 1..2..3 thing at all, so we're having to use something different with him, but with my oldest it works quite well (and the 3-year old is starting to get the idea we're serious when we use it, it's just not quite as good response).
All of that said, if you're still desiring an alternative, perhaps use A..B..C? (although the programmer should also quail at using simple variables, but hey?). Or green... yellow... red? (this may not work depending on favorite colors, etc.). My kids are starting to learn that when I say "I'm very disappointed", they know that they did something wrong, that may work as well, although it's more of a post-event statement as opposed to a get-your-attention statement.
Comment: My parents used a countdown (frequently), and usually physical punishments were counted as well. I grew up to be a computer programmer; I have always loved math. I don't think using numbers in corrective scenarios will affect the love for numbers.
Comment: We use numbers too... what my son learns is that he can procrastinate until the last second :)
Answer: I wouldn't worry about this- it's the act of counting, showing the time in which he has to act is decreasing, and not the actual numbers themselves that he will be responding too.
Kids are tougher than you think- using numbers in this way isn't going to give your child a fear of maths.
Answer: We really tried avoiding 1,2,3 with our son, preferring time outs, but time outs just weren't that effective.  So long as 3 reliably results in a consequence he does not like, he generally responds as desired.  (For him, he wants to do stuff himself, so the consequence is usually getting picked up or us doing the thing for him.)
We also use 1,2,3 as the count when doing hide and seek and other games, so he's learned that numbers can be a lot of fun.  He enjoys counting to ten and then jumping (into pool, off couches, etc.)  Counting objects can also be a fun past time.
So, if it is working keep using 1,2,3 and task your husband with coming up with clever ways of making numbers fun, and you'll not have any trouble at all.
Answer: I really think kids learn quickly that numbers are rather neutral in the good/bad dichotomy.  If this is a serious concern, the best way to neutralize the situation would be to make sure you use positive number examples as well.  Such as, when you give him a treat, like M&M's or a snack like cheerios, ask him to count them to see how many he has.  If he counts correctly perhaps even give him a few more.
Answer: First, I would reassure you, as did one of the other responses, that counting will not impact is perception like/dislike of math.  In the mind of the child, one is about time and the other is altogether different.
Second, I would actually suggest reversing your counting.  I know it seems like a simple difference and in the end - even to a child it isn't a big difference, but 3,2,1, does actually work better in my experience (preschool teacher and mother of my own).
Third, I would also suggest that perhaps it isn't a problem of your child not understanding that you "mean business" but perhaps he is hearing "no" too much.
Please don't get me wrong - kids need to be told no, AND yours needs to stay out of the toilet, but one of the problems parents run into is when we say no too much it loses its meaning.  Think about it, when you hear a word too much, it stops meaning very much.  What curse word do you hear most often?  Does it sound as jarring to you as a curse word you rarely hear?  I say "come on" to Alice all the time and it does absolutely nothing to speed her along, but if I say, "we've got to go quickly" she totally kicks it into gear (I need to be in less of a hurry with her is what it really comes down to for me).  With things like playing in the toilet, your child might just be bored and need some redirection (offer up something more satisfying to you that will be fun to him to replace the toilet), whereas with running into the street you need an immediate response if you say "no" or "stop".
You might like my article, "the magic of toddler water play" if he likes splashing in the toilet, you might get a few "replacement" ideas with which to entice your little gentleman.  pinchxeverything.blogspot.com
Good Luck.

Alternative to the 1-2-3 rule needed


How do you tell if your fermentation is stuck?

Question: How long do you wait before taking corrective action if your fermentation doesn't start?  Are there any other good ways to tell if it's just taking a while to get going?
Comment: Did you use a starter? Dry or wet yeast? How long has it been since you brewed it? Is it within the suggested temperature range?
Comment: This isn't a specific instance- just wondering what rules of thumb apply and what factors might contribute to determining when to start trying to fix it.
Answer: I generally wait a few days before worrying at all.  I have had slow fermentations, where I didn't see any activity in the airlock, but when I took a hydrometer reading after about 10 days, fermentation was complete, so definitely don't assume you have problems simply because you don't see any airlock activity.
Most importantly, make sure your wort is in the appropriate temperature range for your yeast.  If you don't have a stick-on thermometer on your fermenter, you should probably get one, they are very inexpensive.
As with all things in this hobby, relax, don't worry, have a homebrew!  Remember that people have been brewing beer for centuries without worrying about all of the technical details we get to fiddle with today!
Answer: I'd say if it doesn't start in 3 days, then bring it up to the higher end of what the yeast likes, then wait another day or two.
If you still don't see any activity, take a gravity reading, if you're still at your OG then you're stuck.
There are some yeasts out there, Wyeast's saison yeast comes to mind, that ferments incredibly slow at room temperature, which is why you should take that gravity reading before repitching.
Answer: Just to add to the other great answers here, I don't think there's much risk in just waiting a few days. I once waited a week (I was out of town) before discovering that I had used some dead yeast. I re-pitched, and when the batch was finished I couldn't tell any difference from previous batches. As long as you keep things sterile it can sit for quite a while with no issues.
Answer: First thing I always do is stick it somewhere warm or wrap my fermenting vessel in a blanket for a day. The two times I've had a stuck ferment, that's restarted it.
I'd also be taking hydrometer readings carefully at this point, to see if it really is stuck, or just slow!
Answer: Depending on what I'm brewing I expect to see bubbelage within a few days or even less. Sometimes its hard to tell if its stuck or slow. For mead my normal technique is to use a heating pad to warm it up to 70 degrees for so if it doesn't get going within a couple of days.


Finding a general solution of $A_n$

Question: Find the general solution to
$ A_{n+1} + 4A_n = n $
I am unsure how to even start the question :S
Comment: For those who saw the other title: sorry.  I believe I misunderstood the question. `:o`
$$$$
For OP: Is this a sequence?  If so, what values of $n$ is it valid for (e.g. $n\ge0$) and what is the start value?
Answer: Split the problem into homogeneous and inhomogeoneous solutions $A_n^{(H)}$ and $A_n^{(I)}$, respectively.  The homogeneous solution satisfies
$$A_{n+1}^{(H)}+4 A_n^{(H)}=0$$
so that
$$A_n^{(H)} = K \cdot (-4)^n$$
where $K$ is some constant.  For the inhomogeneous solution, you guess a form that will make the left side equal to the right side; in this case, a linear form will do:
$$A_n^{(I)} = a n + b$$
where you substitute into the equation and find $a$ and $b$ by equating constant and linear terms.  The solution is then
$$A_n = A_n^{(H)} + A_n^{(I)}$$
You then find the constant $K$ by using an initial condition (which you did not specify).
Answer: Let $B_n = A_n + an+b$. We then have
$$B_{n+1} + 4B_n = A_{n+1} + an + a + b + 4A_n + 4an + 4b = (5a+1)n + a+5b$$
Choosing $a = -\dfrac15$ and $b = \dfrac1{25}$, i.e., setting $B_n = A_n - \dfrac{n}5 + \dfrac1{25}$, we get
$$B_{n+1} + 4 B_n = 0$$
This gives us $B_n = (-4)^n B_0$. Hence, $$A_n - \dfrac{n}5 + \dfrac1{25} = (-4)^n \left(A_0 + \dfrac1{25}\right) \implies A_n = (-4)^n \left(A_0 + \dfrac1{25}\right) + \dfrac{n}{5} - \dfrac1{25}$$
Comment: @MarkBennet Yes. Thanks. Corrected.
Answer: The answer to this kind of question comes in two parts (there is a strong analogy with linear differential equations).
Suppose $B_{n+1}+4B_{n}=0$ then you can check by linearity that $C_n=A_n+B_n$ satisfies the original equation. And you can compute $B_n$ in terms of $B_0$ without difficulty.
You are left with needing a particular solution for $A_n$ - and first off the guess for a linear expression in $n$ is a linear expression in $n$: - $A_n=pn+q$ will normally work. Sometimes, in similar problems, you will need to increase the degree so that you have terms in $n^2$. Find $p$ and $q$ and then add the sequence for $B_n$ which gives you the right initial value.

Finding a general solution of $A_n$


I am looking at buying a tacx turbo trainer however I am only putting out about 200w on a bike

Question: Is this enough for a turbo trainer and if so, which tacx should I buy?I am looking at a tacx blue or satori as these are in my budget however will the satori be to hard to ride as it has a max output of about 1000watt?
Comment: So the **max** is 1000W and you are producing 200W - doesn't sound like there is a problem there.
Comment: 200 watts sounds about right.  I used to cruse at that level before my legs started going.  I've seen guys at my club doing 500 steady for 15 minutes, but they're gorillas.
Answer: I got a Tacx Flow two or three years ago, so my answer is based on this. Also I don't use it all that much...
As regards power output, I have never measured mine when riding on the open road. I have only ever got power readings when using the turbo. I generally get readings from the headunit in the 200W range (probably anything between 150 and 400 depending on effort) but the flow itself is plenty easy enough to ride. Now how closely my turbo-calculated 200W will tally with your 200W is anybody's guess, but my gut feel is that there won't be a problem with them being too hard to ride.
If you're stuck between the Blue or Sartori I can't help much there. But what I would say is that if you can afford to go up to the Flow, then although out-of-the-box it is "just" a trainer, you have the possibility to upgrade to use the Tacx VR software at a later date. I do not believe that anything beneath the Flow gives you this option, and this was my reason for settling on the Flow.
So if that's something you might want to do in the future.... well buying the VR upgrade for the Flow will be cheaper than buying a new VR turbo.
Answer: I have a satori, but should be similar with other trainer. The satori has 10 resistance settings. In addition to that, you still have your bike gears to adjust the load, so you can spin fast with very light load. So you shouldn't worry that it will be too hard to spin.
To give some illustration, the lightest setting should be rideable for anyone who can ride a bike. #3 setting with max gear on the bike should be pretty hard for someone with 200 w.
Answer: You should not worry - You can shift to an easier gear and work on your fitness. This is what the smaller rings at front are for. You will get more watts later.
I am having the opposite problem - I have rollers and I am turning cranks at 110 rpm and this gives me resistance around my threshold power for an hour.


Broken window crank handle

Question: I'm working on a 1998 Ford Contour with manual windows that has partially broken crank handles on both sides in front.  The knob you grip while rotating the handles has broken off, which makes it annoying to roll the windows down or up.  What's the procedure for removing and replacing the handles?  What's the part number for a replacement handle?
Comment: Just saw this via the meta: I think this question could use some work to help those answering but is, at heart, a good question.  Maybe a picture of the part in question, where the break is, etc.
Answer: There is a small clip behind the handle that retains it to the regulator shaft.You have several options to repair it. The first is to pry on the handle until you destroy the clip and replace it when you install the new handle. Using this method generally results in a damaged door panel also. Any auto parts store sells a door panel tool for under 10 bucks that removes the clip without damage to the door panel. The third option is to locate a window crank knob. Most auto parts stores have a display rack that has items from a company called "HELP" it is a division of Dorman. They specialize in small items that frequently break or get lost. You may be able to find a knob that can be installed without taking off the handle.
Answer: There is a clip holding the handle on the shaft.  You can see it if you gently pry the opening between the base of the handle shaft and the trim piece attached to the door.  I've seen reports of removing it with a knitting needle or working a shop rag into the gap.  I use a wire coat hanger.  A thin piece of metal would be ideal, such as the tool mikes mentioned in his answer.  If you're trying to pull the clip off, there is a loop on the opposite site from the handle shaft.  If you're trying to push it off with something, you want the other side.
Once the clip is off, the handle comes right off the shaft.  As for a replacement part, I've seen the handles at Autozone that mikes mentioned.  They'd probably work just fine, but I went to the parts department at a Ford dealer and had them order two handles.  The part I got was F8RZ-5423342-AAB.  If I plug that into the Team Ford Parts Online site, that comes back as a crank handle for a 2000 Contour.  It's a very close match, I attribute the slight difference to sun fading on the old part.  The color I got was grey, the Team Ford listing says 'order by color'.  Another source would be a "do it yourself" junkyard such as Pick 'n Pull.
As for installing a new handle, just slide the handle onto the shaft with clip in place.  Rotate the handle to line up with the trim piece on the door and push gently.  With a little pressure, the clip will slide into place and hold the handle on.
If you could find just the knob somewhere, it looks like it's possible to remove it from the handle, but I think it would be tricky without taking the handle off first.  I think you would need to push what was left of the old one off from the back.

Broken window crank handle


What uses are there for basil flowers?

Question: I have tons of basil in my herb spiral.
However, this stuff is precious, and I always feel bad when I throw away the basil flowers when I make pesto sauce.
Is there a way to use the basil flowers when cooking?
Comment: My bees think they are the bees knees! They love the flower of the African blue basil and bring life to the yard. I pinch them back after a while because the plant gets tired of supporting all those flowers and make pesto!
Answer: If you pinch off the basil flowers as they start to grow, the plant will produce more leaves. (Yes, this is a horticultural answer, but it will help you make more yummy dishes with the leaves.)
Comment: I've also been told, and found through experience, that the more flowers are produced, the less sweet the leaves become.  I definitely recommend pinching off the flowers before they actually become flowers.  Bonus: where you pinch the stem, the two leaves will become main stems, so you can keep making the plant more bushy as you trim it!
Comment: Thanks for all the answers, this is indeed what I will do. (Basically turn the flowers in to more leaves by pinching the flowers).
Answer: If you wanted to use them in cooking, I would recommend putting them in a sachet (a small pouch made of cheesecloth/muslin tied with cooking twine), as I know some people who don't actually like to eat the flowers, but enjoy the bitter tang they'll add to a dish.
They are edible, however, so if it turns out you like them, they make a beautiful garnish for a salad.  I'm not a huge fan, so I generally stick with Martha's suggestion and keep them pinched so the plant produces more leaves.
Once the flowers appear, the plants energy and resources become more dedicated to flowering, and the leaf growth suffers.  As mentioned in my comment on Martha's answer, I find that when the leaf growth suffers, the flavor of the leaves suffers as well.
This site recommends putting the basil flowers in olive oil, shaking, and leaving on a window sill for a month to make a light basil olive oil.  I've never tried this, and I'm interested, though I'm a little wary of leaving olive oil in a clear container in the sun for a month.  The general idea seems cool, though.
Comment: I'd be worried about the food safety of leaving them covered in olive oil for a month. Doing that with garlic risks botulism. No idea why it wouldn't with basil flowers (unless they were fully dried first, I suppose)
Comment: @derobert, I believe garlic is especially prone to botulism as it goes bad, FWIW.   If I were to try this, I'd probably store it out of the sun (or at least not in a super-hot spot) - tightly sealed.
Answer: I love basil flowers.  They are so much fun and I use them all the time.  I have noticed that different varieties of basil at different times of the summer/growth stage will result in more bitter or delicate tasting buds.  You'll just have to experiment, but I have definitely had some really floral tasting flowers this summer.
I'll throw them into a pesto for a more complex, slightly bitter flavor - I just make sure to pick off any woody stems.
They are a beautiful garnish for just about any stonefruit (plums, peaches, nectarines) - how about roast some fruit, serve with ricotta and some honey...with basil flowers? They are gorgeous in salads or panzanella....anything with tomatoes.
Finally, my favorite thing to do is use them to make basil flower ice cream.  Steep them along with basil leaves in a plain ice cream base and remove them once you have achieved the flavor you desire.  Keep in mind the flavor will develop if you let the base sit overnight (which I recommend) and it will also continue to strengthen a tad as it sits in the freezer. This is generally not a problem if you are making a small batch at home, but more of tip for professionals.
Answer: Yes, you can use them just as you'd use basil leaves. They're generally milder tasting and more decorative in your dish.
Also - from flowers to seeds - a new harvest is also an opportunity.
Comment: You find them more mild tasting?  I've always found them extremely bitter.
Comment: Interesting. Perhaps a species/subspecies thing?
Answer: Vinegar. Pinch off the blossoms and pack them in a jar, cover with white vinegar, seal and keep in the fridge for a few weeks to flavor through... Then discard the blossoms and use the vinegar for dressings or marinades. Delicious stuff... Use sparingly though!
Answer: If you grow African Blue Basil, you'll have a TON of flowers that are not at all bitter at any time. We use them in all kinds of cooking, but our favorite use is to make Basil Bud Ice Cream. Literally the best ice cream I've ever tasted. The flavor of these flowers is the basil itself with strong floral overtones that mesh well. Great fresh as a salad topper too.
Honestly, you haven't lived until you try growing African Blue Basil. Everyone raves about it and everything we make with it. Just finished a MONSTER batch of pesto to keep us through the winter. Best plant I've ever grown, bar none. We had about 50-60 plants this year. Also, definitely top them as they grow in tridents and by topping them, you cause them to bush out a lot more dramatically.
Answer: Using basil flowers in my fresh tomatoes I'm cooking down to can is Excellent! Strong in flavour but I like that. If you don't dilute it! :-) ~
Answer: Dry basic flowers can be used to make a awesome little potpourri pouch or a small sachet :)
Answer: Basil flowers can be eaten, for instance in soup.
Comment: Hello, and welcome to the site! As you can see, I changed your answer a bit. Don't worry, this is pretty normal on the stack exchange sites! To clarify, I corrected your English a bit. I also deleted the link you posted, since I did not see the relevance. Why did you put that link there exactly?
Answer: I love putting the flowers along with lavender, lemon balm and mint in some water and once it almost hits boiling point putting it on low then drinking as tea. Super yummy.
Comment: I've removed the implicit health question - this is an answer, not a question, and health is off topic here anyway. (We're a food and cooking site.) With that gone, I think this is actually a pretty reasonable answer - no one else suggested tea.
Answer: I plant Basil along with my Tomatoes to deter insects.  One Basil Plant every fifth Tomato Plant, and it really works quite well. I keep cutting the flowers off until near the end of the Tomato season, and then let them go. I have some African bushes that are three feet tall, and app. three feet in diameter. I usually give most away as either fresh, or I hang them in the shed to dry for people who like to preserve them.  We do use some for flavoring, especially when we can Salsa or other Tomato products like juice, soup mix, etc.
Answer: I grow Queen Siam Thai Basil and Genovese Basil.
I use the flowers in soups and pesto mostly and I don't notice them being bitter or making the leaves bitter once the plants start flowering. The flowers do seem to have a condensed flavor. I do however snip the basil leaves while they are young and smallish since the taste seems cleaner and fresher when small.
Answer: Honestly, I use them as a sign that it's time to toss the basil plant.
Comment: @Ranieri - using Martha's suggestion, there's no need to toss the plant.  Pinch them off and watch your plant flourish!
Comment: Basil that has flowered almost always drastically changes flavor, getting that hot peppery taste and losing the delicate taste it had beforehand.  It's a matter of taste, but I would toss the plant too.
Answer: I leave them on the plant because the bees just love them. I grow basil mostly for the bees now. The bees need our help. When they go we go.

What uses are there for basil flowers?