I have a machine which I have accidentally install 32-bit 12.04 LTS on.  (Yes, accidentally. I can't recall how I managed that.)  What is the easiest way to fix this? Mucking about with the kernel files or axing it with a reinstall?  Is it possible and safe to have a dual boot of 32 and 64-bit 12.04 LTS?
I've got a 32-bit Ubuntu installation running on 64-bit hardware. Now that , I would like to switch to 64-bit without having to reinstall the OS.  This is one of the :  Shawn installed his system using the 32-bit version of Ubuntu, but his hardware is 64-bit and he wants to switch over. He manually installs the amd64 versions of dpkg and apt, replacing the i386 versions and changing which architecture is used as the default; then he installs the amd64 ubuntu-minimal package; then he installs the amd64 ubuntu-desktop package. Over time the remaining i386 packages are replaced automatically on upgrade.  However, when trying to follow the instructions in there, I cannot find any 64-bit version of dpkg or apt.  Did this user story got implemented in a different way in the final spec, or do I need to do something differently?  In short, how can I switch my 32-bit installation to 64-bit?
Url rewriting in Amazon S3 I have a webapp hosted in Amazon S3, the webapp is build with jQuery Mobile and I use changePage lo navigate between pages, I'm not using the hash operator(#) when I change the page.  I'm having problems when the user copy the url and paste it in a new tab  For example:    loads the page page1.html that is in amazon s3 with only the jquery page structure...  The behavior that I want is that load index.html and with js read the url, detect the page and load the correct page.  With Apache I solve this with URL Rewriting... but for Amazon S3 I didn't find any similar...  NOTE: I know that if I activate the hash operator (#) in my urls the problem is solved but I need clean urls without #. PHP eval issue with PHP + HTML code Integral of sinc function multiplied by Gaussian I am wondering whether the following integral $$\int_{-\infty}^{\infty}  \frac{\exp( - a x^2 ) \sin( bx )}{x} \,\mathrm{d}x$$ exists in closed form. I would like to use it for numerical calculation and find an efficient way to evaluate it. If analytical form does not exist, I really appreciate any alternative means for evaluating the integral. One method would be numerical quadrature including Gaussian quadrature, but it may be inefficient when the parameters $a$ and $b$ are very different in scale.  EDIT : In view of  discussion, we have decided to add OP's self-answer to the end of the question, for it does not qualify as an answer yet contains vital details. The copying is unabridged. Thanks very much for your comments, and the following result was obtained including the case for $x_0 \ne 0$: $$ \int_{-\infty}^{\infty} dx \exp[-a(x-x_0)^2] \frac{ \sin(bx) }{ x } = \pi \exp(-a x_0^2) \mathrm{Re}\left(\mathrm{erf}\left[\frac{b+2iax_0}{2\sqrt{a}}\right] - \mathrm{erf}\left[\frac{2iax_0}{2\sqrt{a}}\right]\right) $$ where $a\gt0, b, x_0$ are assumed to be all real. (note: coefficients etc may be still wrong...) This integral appears in a type of electronic structure calculation based on a grid representation (sinc-function basis). I believe the above result should be definitely useful. Thanks much!! --jaian I installed Ubuntu on a Dell XPS 13 laptop that had Windows 10 preinstalled on it. I installed it from a USB flash drive on a partition. When I boot my computer I can only boot into Windows 10 and Ubuntu is nowhere to be seen.  If I boot into my USB then I can see that Ubuntu is installed, but I can't get to it from the BIOS boot menu. I would like to have a similar biblatex behaviour as described , i.e. separate bibliographies for different publication types, each bibliography should 1) be prefixed with a corresponding label (C for conference publications, J for journals etc), 2) sorted so that the newest entry is at the top (defined by the publication year) and 3) with reference numbers sorted in descending order per bibliography, i.e. the newest entry should have the highest number.  Journal articles ---------------- [J3]    reference from 2017 [J2]    reference from 2016 [J1]    reference from 2015  Conference publications ----------------------- [C4]    reference from 2017 [C3]    reference from 2017 [C2]    reference from 2016 [C1]    reference from 2015   I currently have the following:  \usepackage[backend=biber,         isbn=true,         giveninits=true,         style=numeric,         maxnames=99,         sorting=ydnt,         defernumbers=true,         autocite=superscript]{biblatex}  \subsection*{Journal articles} \begin{refcontext}[labelprefix=J] \printbibliography[type=article] \end{refcontext}  \subsection*{Conference publications} \begin{refcontext}[labelprefix=C] \printbibliography[type=inproceedings]   Separate bibliographies works fine, labelprefix also works as desired, sorting by year in descending order as well. However, if I try the solution mentioned in the above question I get very high reference numbers (in the 500s).  Is the above behaviour possible at all and, if yes, what is the most elegant solution using current biblatex etc.?  Thanks a lot in advance! Use #ifdefs and #define to optionally turn a function call into a comment Is it possible to do something like this  #ifdef SOMETHING #define foo // #else #define foo MyFunction #endif   The idea is that if SOMETHING is defined, then calls to foo(...) become comments (or something that doesn't get evaluated or compiled), otherwise it becomes a call to MyFunction.  I've seen __noop used, but I don't believe I can use that.  EDIT(s):  I don't think I can really use a macro here, because MyFunction takes a variable number of arguments.  Also, I'd like to make it so the arguments are NOT evaluated!  (So doing something like commenting out the body of MyFunction doesn't really give me what I need, as the arguments will still be evaluated) Blank questions and answers I have white blank on the posts.    App Version: 1.0.89 Device Manufacturer: Meizu Device Model: m2   OS Version: 5.1 (1464689330)    I can't see the questions and the answers and the comments.  I saw that it's a common issue..  Does it have a fix?   EDIT -  I saw  answer. This answer is ~2 years old. It says that it will fix in the next update.  His version is 1.0.59 - mine is 1.0.89. Huge different.   The problem is still exists! How do you show monotonicity of the $\ell^p$ norms? I can't seem to work out the inequality $(\sum |x_n|^q)^{1/q} \leq (\sum |x_n|^p)^{1/p}$ for $p \leq q$ (which I'm assuming is the way to go about it). Are the units of the quotient ring $\mathbb{F}_2[x]/\langle x^k+1 \rangle$ known in general, where $\mathbb{F}_2$ is the finite field with two elements? I'm specifically interested in the case where $k$ is divisible by two, such as say $k=8$, or $k=12$.  If so, can they be constructed easily? I'd be grateful if you could provide a few examples. Show that $\lim\limits_{y\downarrow 0} y\mathbb{E}[\frac{1}{X};X>y]=0$. Let $(\Omega,\mathcal{F},\mathbb{P})$ be a probability space, and let $X$ be a nonnegative random defined on this space. For any $A\in \mathcal{F}$, let $\mathbb{E}[X;A]:=\mathbb{E}[X\mathbb{1}_{A}]$, where $\mathbb{1}_{A}$ denotes the indicator random variable on $A$. Without assuming $\mathbb{E}\left[\frac{1}{X}\right]&lt;\infty$, show that  \begin{eqnarray} \lim\limits_{y\downarrow 0} ~~y~\mathbb{E}\left[\frac{1}{X};X&gt;y\right]=0. \end{eqnarray} Any initial ideas will be greatly appreciated. (a) Solve the equation $yu_x+xu_y=0$  with the condition $u(0,y) = e^{-y^2}$. (b) In which region of the xy plane is the solution uniquely determined?     I did the first part but I don't understand how to do part b.  I read   But I don't understand how the argument is based. A more clear explanation is appreciated Anyone know if R has quote-like operators like Perl's qw() for generating character vectors? Two envelope problem revisited I was thinking of this problem.  I believe the solution and I think I understand it, but if I take the following approach I'm completely confused. Problem 1:  I will offer you the following game. You pay me \$10 and I will flip a fair coin. Heads I give you \$5 and Tails I give you \$20. The expectation is \$12.5 so you will always play the game.  Problem 2:  I will give you an envelope with \$10, the envelope is open and you can check. I then show you another envelope, closed this time and tell you: This envelope either has \$5 or $20 in it with equal probability. Do you want to swap? I feel this is exactly the same as problem 1, you forgo \$10 for a \$5 or a \$20, so again you will always switch.  Problem 3:  I do the same as above but close the envelopes. So you don't know there are $10 but some amount X. I tell you the other envelope has double or half. Now if you follow the same logic you want  to switch. This is the envelope paradox.  What changed when I closed the envelope?? EDIT: Some have argued that problem 3 is not the envelope problem and I'm going to try and provide below why I think it is by analysing how each views the game. Also, it gives a better set up for the game. Providing some clarification for Problem 3: From the perspective of the person organising the game:  I hold 2 envelopes. In one I put \$10 close it and give it to the player. I then tell him, I have one more envelope that has either double or half the amount of the envelope I just gave you. Do you want to switch? I then proceed to flip a fair coin and Heads I put \$5 in and Tails I put \$20. And hand him the envelope. I then ask him. The envelope you just gave me has twice or half the amount of the envelope you are holding. Do you want to switch?  From the perspective of the player:  I am given an envelope and told there is another envelope that has double or half the amount with equal probability. Do I want to switch. I think sure I have $X$, hence $\frac{1}{2}(\frac{1}{2}X + 2X) &gt; X$ so I want to switch. I get the envelope and all of a sudden I am facing the exact same situation. I want to switch again as the other envelope has either double or half the amount. I have an uploaded video and I want to cut sections of audio (strong language) or add beeps on top without reuploading the video. Is there a way to mount a disk directly to a specific folder? For example, I can't install package qcad because of error: "can't find qdict.h". How can I find the package which provides the file qdict.h so I can install the package qcad? Best way to capture historical changes between levels in a dimensional hierarchy What is the cleanest way to capture changes between levels in a dimensional hierarchy?  I have the dimensional hierarchy [Area] > [Region] > [Location], where Area is the parent to Region and Region is the parent to Location. Location is lowest level of the hierarchy, and is associated with the fact table.  The business rules are: Locations are able to change the Region they are assigned to based on business need. Furthermore, Regions are able to change the Area they are assigned to.  We want to capture those changes so that when we do historical analysis, we can compare business metrics before and after a Location changed its Region, and a before and after a Region changed its Area.  What is the best way to do this?  The four ways that I have come up with all seem to have major drawbacks:   Using a bridge table between hierarchy levels requires that you use time bounds (effective start/end dates) to correctly identify which parent a child belongs to as you walk up the hierarchy. That makes queries prone to error, especially with hierarchies with many levels. Versioning a child record whenever its relationship to its parent changes (e.g., versioning Region A when it moves from Area A to Area B) and then cascading that change all the way down the hierarchy (e.g., creating new versions of Locations tied to Region A so that they are tied to the new Region A). Updating the child record's reference to the parent record, making you use time bounds to reassemble the correct history (prone to error). Always use time bounds when querying up the hierarchy to make sure Location A is associated with the correct Region (likewise, Region A is associated with the correct Area) for the moment of the fact being analyzed.   None of these seems clean to me.  Is there a better way?  Thanks a lot Best practices for catching and re-throwing .NET exceptions Debugging a custom-bib bst file that crashes on book items I created my own bibliography file with custom-bib (makebst), but when I run it with a reference to a book I get:  $ bibtex PhD [...normal output] Database file #1: PhD.bib You can't pop an empty literal stack for entry oecd2001brc while executing---line 1504 of file wdsphd.bst   The only thing on that line is a high-level ITERATE call.   The style was created with these options:  %% merlin.mbs  (with options: `head,exlang,annote,seq-no,nm-rvvc,dt-beg,yr-par,xmth,tit-qq,qx,bt-qq,vol-bf,volp-sp,num-xser,pub-date,isbn,issn,doi,english,pp,ord,url,url-nl,nfss,,{}') %% english.mbs  (with options: `exlang,annote,seq-no,nm-rvvc,dt-beg,yr-par,xmth,tit-qq,qx,bt-qq,vol-bf,volp-sp,num-xser,pub-date,isbn,issn,doi,english,pp,ord,url,url-nl,nfss,,{}') %% merlin.mbs  (with options: `tail,exlang,annote,seq-no,nm-rvvc,dt-beg,yr-par,xmth,tit-qq,qx,bt-qq,vol-bf,volp-sp,num-xser,pub-date,isbn,issn,doi,english,pp,ord,url,url-nl,nfss,,{}')   The code for book items looks like:  FUNCTION {book} { output.bibitem   author empty$     { format.editors "author and editor" output.check     }     { format.authors output.nonnull       crossref missing$         { "author and editor" editor either.or.check }         'skip$       if$     }   if$   format.btitle "title" output.check   crossref missing$     { format.bvolume output       new.block       format.number.series output       new.sentence       format.publisher.address output     }     {       new.block       format.book.crossref output.nonnull     }   if$   format.edition output   format.isbn output   format.doi output   new.block   format.note output   fin.entry   write.url }   And this is the entry:  @book{oecd2001brc,  author = {OECD},  doi = {10.1787/9789264193550-en},  isbn = {9789264186903},  publisher = {OECD Publishing},  title = {{Biological Resource Centres: Underpinning the future of life sciences and biotechnology}},  url = {http://www.oecd-ilibrary.org/science-and-technology/biological-resource-centres\_9789264193550-en},  year = {2001} }   Is there a way to get a better stacktrace from bibtex? What I have now doesn 't really tell me what is going on. If it can be fixed simply, help would also be appreciated. Are "white" and "black" ever capitalized when referring to people?