My 3.0 portable HD was corrupted, I've got personal data on it and I wanted to prevent any randoms from accessing it. I am not very tool-savvy, so I just broke the circuit board, and repeatably bashed it with a hammer on both sides. I wasn't able to access the platter but I did hear some broken shards on the inside traveling around when I would shake it, so I either broke the platter just by hitting with impact, or there was something else in there that broke. Thoughts?
I have 3 old 3.5" internal hard drives sitting gathering dust at the moment. 2 are SATA, and one IDE. I want to either start putting them to use, or dispose of them to clear up some space.  What is the best approach towards disposing of the drives in terms of thoroughly cleaning the contents before throwing away or selling? Are there any recommendations for good software to use to do this?   Are there any 100% successful methods which result in having a usable drive at the end?
An easy bash completion tutorial? How to run a complete GUI as root? Book series where they collect either stones or gems I'm looking for a fantasy book I read about 10 years ago. I don't remember a lot of it, but there are a few things I still know:   The setting was in medieval times. There was no traveling dimensions. I can't recall whether there was magic or not. It wasn't on Earth, but on some invented world. I believe it was a trilogy, with a focus on the son of some nobility. The goal for the characters was to collect a certain number of stones or gems (I believe there were 5 of them), all in certain colours. Every stone has a certain power attached to it. I believe it started out with one or two characters, but the group grew and every character had a certain colour stone at the end. What is important about the gems is that they are unique. It's not part of a bigger magic system, but they are artefacts from somewhere.   There are some minor incidents I can recall vividly:   They build up a fellowship with some stereotypical fantasy builds: an old school fighter, a minstrel, a female archer and probably more. At one point, they mention that if one of the guards in a country falls asleep on duty, he will be kept awake by his garrison/brothers in arms for seven days. At some point the minstrel falls asleep, and the old fighter teaches him how to stay awake. They travel through a forest full of leeches and other insects to reach one of the stones. Also, I seem to recall there was a member of an underground evil organisation among the nobility, who tried to poison someone and were able to do that because they built up an immunity to the poison.   Does anyone has a clue what this series might be?   Suggestions by kind people, but not what I'm looking for, are:   The Seventh Tower Deltora Quest Diadem Westria Sword of Heavens series Android app intermittently shows blank body in questions and answers (multiple sites) Creating fillable PDFs I'd like to create a LaTeX document that when rendered into PDF, has forms that can be filled out using Adobe Reader or other such programs. Then I'd like to be able to extract the data. I deliberately would like to avoid using Acrobat for all the usual reasons (non-free, need different versions for different platforms etc).   Can this be done ? Help with proof that $\mathbb Z[i]/\langle 1 - i \rangle$ is a field. I have been having a lot of trouble teaching myself rings, so much so that even "simple" proofs are really difficult for me. I think I am finally starting to get it, but just to be sure could some one please check this proof that $\mathbb Z[i]/\langle 1 - i \rangle$ is a field. Thank you.  Proof: Notice that $$\langle 1 - i \rangle\\  \Rightarrow 1 = i\\  \Rightarrow 2 = 0.$$ Thus all elements of the form $a+ bi + \langle 1 - i \rangle$ can be rewritten as $a+ b + \langle 1 - i \rangle$. But since $2=0$ this implies that the elements that are left can be written as $1 + \langle 1 - i \rangle$ or $0 + \langle 1 - i \rangle$. Thus  $$ \mathbb Z[i]/ \langle 1 - i \rangle = \{ 0+ \langle 1 - i \rangle , 1 + \langle 1 - i \rangle\}. $$  This is obviously a commutative ring with unity and no zero-divisors, thus it is a finite integral domain, and hence is a field. $\square$ How to change the line spacing in my list of figures? I am using the book documentclass and have a list of figures. After  I noticed that there is a blank line to separate figures that are in different chapters, but not if they are within the same chapter. Since I changed the numbering of my figures to be {1, 2, 3, etc.} instead of {2.1, 2.2, 3.1, etc.} this looks silly and I'd rather have a blank line between each figure, no matter what.  How do I do that?  Similar: Sum of columns for rows containing a specific term Just need help understanding this question, as I don't really understand what a continuous random vector is. My limited understanding is that a continuous random vector must be completely continuous (so for continuous X and Y this is satisfied) and that to get the probability of the random vector occurring, we double integrate over the supports (of X and Y obviously). My guess is then, that the c.r.v (X,Y) IS a continuous random vector.  Also, what of the converse? If (X,Y) is a continuous random vector, then are X and Y continuous random variables? I also think this is correct, as the continuity of the vector MUST imply the continuity of X and Y, although I'm honestly not sure.  Thanks Showing that $\mathbb{Q}[\sqrt{2}, \sqrt{3}]$ contains multiplicative inverses Why must $\mathbb{Q}[\sqrt{2}, \sqrt{3}]$ -- the set of all polynomials in $\sqrt{2}$ and $\sqrt{3}$ with rational coefficients  -- contain multiplicative inverses?   I have gathered that every element of $\mathbb{Q}[\sqrt{2}, \sqrt{3}]$ takes form $a + b\sqrt{2} + c\sqrt{3} + d\sqrt{2}\sqrt{3}$ for some $a,b,c,d \in \mathbb{Q}$, and I have shown that $\mathbb{Q}[\sqrt{2}]$ and $\mathbb{Q}[\sqrt{3}]$ are both fields, but it's not clear to me why this allows for general multiplicative inverses to exist in $\mathbb{Q}[\sqrt{2}, \sqrt{3}]$. At which embassy should I apply for a Schengen visa when staying a few days in several countries? I'm planning to go to Germany on Sept 6-8, then Netherlands on Sept 8-11 and exit Switzerland on Sept 11-14.  My question is:  Which embassy do I need to apply for the Schengen visa? The number of days are the same for Netherlands and Switzerland, but I'm planning to apply in Netherlands since it will be my second point of entry. Should Emergency Funds be Used for Infrequent, but Likely, Expenses? Say we break down non-monthly costs into the following three categories.   High level of predictability: This would include oil changes that may be needed every 2 to 4 months depending on usage, car insurance (if paid every 6 month), car registration, etc. Medium level of predictability: There are some expense which one can reasonable assume will occur on an infrequent basis.  For example, car repairs, house repairs, or even doctor visits during flu season. Low level of predictability: For example, losing a job, significant medical expense, etc.   Which of these categories are emergency funds meant to cover?  I think it is pretty clear that a high level of predictability costs should not use emergency funds while a low level of predictability should.  But medium level of predictability costs seem different, and it left me wondering what is generally defined as an "emergency".  While you do not know when these costs will occur or how much they will be, you could devise some pretty good rules of thumb on frequency and cost. Say you know your 2007 Volvo should have a repair cost averaging out to $100 per month.  Conceptually you could save $100 each month and when your car breaks, not have to spend any emergency funds on the repair.  Is doing this "double-saving" and not suggested if you already have the 6 month emergency fund saved up?  Note: this is a question on how to save money for expenses.  It is not a question about if you should spend emergency fund money to fix a car when you have no other money set aside. I hope it is alright to ask something like this here, I am having trouble keeping up with all the special cases and my book is being kind of vague.  I know how to do the standard method of finding diagonal matrices, but I know that triangular matrices are special and my book makes a connection, but it is hard to tell what it is.  Thanks. I am attempting to settle a friendly bet.  Would a pendulum swing indefinitely in a hypothetical vacuum (i.e. no air resistance) having a hypothetical frictionless bearing (i.e. no energy lost due to friction) assuming the following   The frictionless vacuum is on Earth (9.8 m/s^2). The pendulum is already in motion and no other external forces other than gravity act on the pendulum. Is the set of real matrices diagonalizable in $\mathcal M_n(C)$ dense in the set of all companion matrices? the numer of partial function between two sets in combinatoric way How to convert QString to std::string? A gold reviewer badge? For your continued efforts in reviewing posts, even though the system sometimes messes up and doesn't let you actually review things and keeps displaying them over and over and over. So also, for your patience in putting up with the glitches in the review panel too! Haha  Anyways, a gold reviewer badge: 20000 reviews, over 4000 actioned  I just multiplied both numbers by 20. Think those numbers seem challenging? Is anyone up near those numbers or should it be multiplied by 10 instead? I prefer the higher amount because it would be gold and something harder to work for. :) But we also have to consider the longevity of when all these posts are eventually reviewed and it's only new posts being created.  Anyways, my stats for those who are interested (I wouldn't get the badge to start because I only have ~2000 actioned):  Upvoted            189 Downvoted          11 Edited             926 Commented          127 Voted to Close     44 Flagged            447 Reviewed           21609   As far as the name of the badge, I really like "The Owl is Watching" but not sure if that would be too long. Sounds snazzy though. Ideas?    Personally, I was on a quest to try and clear out all the posts in a single tab before it started showing me the same things over and over (and over) and then it got frustrating because I wasn't even making progress. Quest denied. :(    Lately I've noticed a massive build-up of unreviewed posts. When the review panel was first implemented, there would only ever be maybe 50 unreviewed posts at a time (in a given tab) for my monthly view. Now I log in and there's a thousand or two thousand pending. I think a lot of people quit reviewing after the first badge, so having a gold badge with a high threshold would really improve activity in the review panel and keep people going to improve the community. For what values of $\theta$ does $\sum_{1}^{\infty} \frac{e^{i n\theta}}{n}$ Converge? I just came across the problem of what happens in the boundary cases of .  More concisely, for what $\theta$ will the following sum converge? $$\sum_{n=1}^{\infty} \frac{e^{ni\theta}}{n}$$ It is well known that this sum will diverge for $\theta=0$ and will converge for $\theta=\pi$. In fact, for any odd multiple of an even root of unity, since we have symmetry, for each line through the origin of the complex plane, we can use the alternating series theorem to show that they converge.  Another idea I had was to split  the sum into imaginary and real parts, and if we can prove each of these converges, then we are all set. So now we must prove that both of the following converge $$\sum_{n=1}^{\infty}\frac{\cos(n\theta)}{n}\space, \space \sum_{n=1}^{\infty}\frac{\sin(n\theta)}{n}$$ Now these can be shown to converge easily by Dirichlet's test for any rational multiple of pi, but what about irrational multiples of pi? I know it has been shown to converge with $\theta=1$, but I don't see how to generalize this. Let $A [a_{i,j}]$  and $B =[b_{ij}]$   be two diagonal matrices in   $M_n(F)$. Let $i \ne j \in \left\{1, \ldots, n \right\}$. Using the   product rule, we obtain      $$(AB)_{ij} = \sum_{k=1}^{n} a_{ik}b_{kj}$$      We claim that $a_{ik}b_{kj} =0$ for all $k \in \left\{1, \ldots, n \right\}$ thus $(AB)_{ij}=0$ for all $i \ne j$ and $AB$ is diagonal. To    prove the claim, note that since $i \ne j$ , we have $i \ne k$ or $    k\ne j$. Thus either $a_{ik} = 0$ (since $A$ is diagonal) or $b_{kj} =  0$ (since $B$ is diagonal), thus in all cases $a_{ik}b_{kj}=0$ and the   claim is proved.   Where does the bit "we have $i \ne k$ or $k\ne j$" come from? I understand that since $i \ne j$, and $k$ and $j$ run over the same set of natural numbers, we also have $i \ne k$. But the "or $k \ne j$" baffles me. I understand that $k \ne j$ implies that we can have $i=k$. But that's from the other direction ($\Longleftarrow).$  Also, when it says $a_{ik}=0$ or $b_{kj}=0$ it's talking about when $i \ne k$ or $k \ne j$ right? Many thanks.