UnboundLocalError: local variable 'balance' referenced before assignment (Python)
UnboundLocalError on local variable when reassigned after first use
Proofs of AM-GM inequality Prevent a part of the caption from appearing in the list of figures I am using the 'article' class, 'figure' environment.  My captions are divided in two parts:   the information about the figure the credits of the figure (for which I use \textfff{})   In my list of figures, I would like to omit the second part. Would you have a solution, please? Cycle option when drawing between nodes in TikZ Cycle lets you close curves when drawing, and  \coordinate (a) at (0,0); \coordinate (b) at (1,0); \coordinate (c) at (0.5, -1); \draw (a) -- (b) -- (c) -- cycle;   works fine. Shouldn't also  \node (a) at (0,0) {}; \node (b) at (1,0) {}; \node (c) at (0.5, -1) {}; \draw (a) -- (b) -- (c) -- cycle;   give the same result?  The former gives a triangle, while the second doesn't close up. Is this a bug or am I missing something regarding the cycle option?  (Of course, as a workaround I could use the coordinates to draw the cycled path, and then draw the nodes at the same coordinates, but still...) Why was the snaphat not awarded? Or why was it awarded incorrectly? There have been a few cases in which the  was not awarded.   There have also been other cases in which it was awarded incorrectly, on old questions.   What gives? Convert from MySQL datetime to another format with PHP I have a datetime column in MySQL.   How can I convert it to the display as mm/dd/yy H:M (AM/PM) using PHP? Relationship between gamma and chi-squared distribution If $$Y=\sum_{i=1}^{N}X_i^2$$ where $X_i \sim \mathcal{N}(0,\sigma^2)$, i.e. all $X_i$ are i.i.d. normal random variables of zero mean with same variances, then $$Y \sim \Gamma\left(\frac{N}{2},2\sigma^2\right).$$  I know the chi-squared distribution is a special case of the gamma distribution, but could not derive the chi-squared distribution for random variable $Y$. Any help, please? I am looking for a short proof that $$\int_0^\infty \left(\frac{\sin x}{x}\right)^2 \mathrm dx=\frac{\pi}{2}.$$ What do you think?  It is kind of amazing that $$\int_0^\infty \frac{\sin x}{x} \mathrm dx$$ is also $\frac{\pi}{2}.$ Many proofs of this latter one are already in this . Where do I find system sounds? After installing gm-notify I see the option of hearing a sound every time a new e-mail arrives in my Gmail inbox, but I don't know where Ubuntu (10.4) stores the system sounds to assign one. Any ideas? Thanks. options for appearance of links in hyperref If I use  \usepackage[colorlinks]{hyperref}   I get colored links for \cite (not good for printing or even viewing) but table of content looks fine.  If I use  \usepackage[colorlinks=false]{hyperref}   I get \cite  links in black with a colored frame (this looks very good) but the table of content looks strange with extra long boxes.  What are my other options? Can you have two styles in different parts of a document?   How do you make the page numbers in TOC to be the links instead of the section headers? I'm trying to update my system using apt-get, but it's giving me this error  Err http://bd.archive.ubuntu.com raring Release.gpg          Could not connect to bd.archive.ubuntu.com:80 (116.193.170.18), connection timed out Err http://bd.archive.ubuntu.com raring-updates Release.gpg   Unable to connect to bd.archive.ubuntu.com:http: Err http://bd.archive.ubuntu.com raring-backports Release.gpg   Unable to connect to bd.archive.ubuntu.com:http: Reading package lists... Done W: Failed to fetch http://bd.archive.ubuntu.com/ubuntu/dists/raring/Release.gpg  Could not connect to bd.archive.ubuntu.com:80 (116.193.170.18), connection timed out W: Failed to fetch http://bd.archive.ubuntu.com/ubuntu/dists/raring-updates/Release.gpg  Unable to connect to bd.archive.ubuntu.com:http: W: Failed to fetch http://bd.archive.ubuntu.com/ubuntu/dists/raring-backports/Release.gpg  Unable to connect to bd.archive.ubuntu.com:http: W: Some index files failed to download. They have been ignored, or old ones used instead.   I am not a Ubuntu master but I can understand this is not a computer error. Any clues on how to fix it? Array slices in C# How do you do it? Given a byte array:  byte[] foo = new byte[4096];   How would I get the first x bytes of the array as a separate array? (Specifically, I need it as an IEnumerable&lt;byte&gt;)  This is for working with Sockets. I figure the easiest way would be array slicing, similar to Perls syntax:  @bar = @foo[0..40];   Which would return the first 41 elements into the @bar array. Is there something in C# that I'm just missing, or is there some other thing I should be doing?  LINQ is an option for me (.NET 3.5), if that helps any. Integral $\int^{ \pi /2}_{0} \ln (\sin x)\ dx$ $$\int^{ \pi /2}_{0} \ln (\sin x)\  dx$$  The answer is $- \frac{\pi}{2} \ln 2$.  I have changed it into $$\frac{1}{2} \int^{1}_{0} t d \ln t^{2}$$  But I didn't get the answer with it. Questions on "All Horse are the Same Color" Proof by Complete Induction I'm bugged by the following that's summarized on p. 109 of .     False theorem: All horses are the same color.      Proof by induction:      $\fbox{$P(n)$ is the statement: In every set of horses of size $n$, all $n$ horses are the same color.}$   $\fbox{Base Case or $P(1)$:}$ One horse is the same color as itself. This is true by inspection.   $\fbox{Induction Step:}$ Assume $P(k)$ for some $k \geq 1$.   $\fbox{Proof of $P(k + 1) :$}$   Since $\{H_1, H_2, ... , H_n\}$ is a set of $n$ horses, the induction hypothesis applies to this set. Thus, all the horses in this set are the same color.   Since $\{H_2, H_3, ... , H_{n+1}\}$ is also a set of $n$ horses, the induction step likewise holds for this set. Thus, all the horses in this set are the same color too.         Therefore, all $n +1$ horses in $\{H_1, H_2, H_3, ... , H_n , H_{n+1}\}$ are the same color. QED.   The issue the instructor was trying to point out is clearly valid. For the case $n = 1$, there is only ${H_1}$. So this case says nothing about possible overlapping elements of each set of $(n + 1)$, for instance $H_2$ in the above proof.    But it was proposed in the class discussion that this was the only problem. Had you been able to prove $P(2)$ true, then a proof of the above format would have been fine.    My interpretation is that yes, you could prove all horses are the same color, if you can prove that any set of two horses will be the same color. But this format would not work.  Why not? The problem I see is that the above proof is for the existence of at least one particular pair of sets of horses of sizes $n$ and $n + 1$, such that in each set, all horses are the same color.  Particularly when the set of size $n$ is a subset of the set of size $n + 1$.  In order to prove the induction step, don't you need to prove that sets of sizes $n$ and $n + 1$, do not necessarily contain the same, overlapping elements?  You could prove that any horse can be added to a set of 2 horses.  Take the last two, and they must be the same color, and so on.  Wwhatever color the first two happen to be, all other horses must thus be the same color.    Am I misinterpreting the example, or am I making a logical error? Thanks in advance. Show that every irrational number in $\mathbb{R}$ is the limit of a   sequence of rational numbers. Every rational number in $\mathbb{R}$ is   the limit of a sequence of irrational numbers.   How can I prove this? Grammar checking program for LibreOffice Is there a tool for checking grammar in LibreOffice? Double-blind review with four references in a row? I've read a lot of answers here about double-blind reviews and thesis or single articles.  My problem comes from having four self-references in my article. I feel that if I include them all, could be very easy to infer that this is the fifth one (It's a 4-year granted project and I have been collaborating in a number of software components inside a bigger architecture, now it's the time to use them all to interact with other applications) . But if I ommit some of them, I could end being accused of self-plagiarism. The other articles have been published in the proceedings of conferences that didn't require double-blind reviews, this is the first submission I make to a conference that asks for it (Maybe because of being CORE A) Also not worthless to mention that I'm going to send it as a short paper, so actually it'd be very helpful to cite rather than to repeat past texts.  What should I do? "Yesterday" time specification shown when it was actually the day before yesterday Looking at , I see "asked yesterday" (which I really hate; I'd like to see an exact time specification rather than this vague one, especially in the list of questions). But it was not asked yesterday! When I hover over it to show the exact time, it shows it was actually the day before yesterday!  This snapshot was taken at 2012-03-31 15:00 UTC (plus or minus a few minutes):    Whatever different opinions you may have on the implementation, yesterday is a word with a certain meaning. Redefining it is not a good idea. At least rephrase this as "1 day ago" or something. I have a .txt file with numbers ordered like this (on the same row):  106849_01373    106849_01967    106850_00082    23025.7_01059      I would like to convert them like that:  106849_01373 106849_01967 106850_00082 23025.7_01059   I have no idea which command to use. Can somebody help me with this? Creating multiline strings in JavaScript Email Templates: Conditional Greeting Based on Time of Day