How to parse arguments by bracket(not parentheses) in python
What does it mean if a Python object is "subscriptable" or not?
It is easy to find the minimum of $\|Ax-b\|_2$, when $A$ has full column rank. But how is the case when we add the constraint $\|x\|_2=1$? Or, to be explicit,  $$\min_{\|x\|_2=1}\|Ax-b\|_2=?$$  My idea is to construct the corresponding Lagrange function  $$L(x,\lambda) = (Ax-b)^T(Ax-b) + \lambda(x^T x - 1)$$  Differentiate the function with respect to $x,\lambda$, we have  $$A^T A x - A^T b + \lambda x = 0$$  $$x^T x=1$$  However, I find it hard to move forward to get the answer. Could anyone help me? Thanks a lot! Complicated FOR loop nesting. Having trouble cleaning up legacy code How to splice together several instances of InterpolatingFunction? Converting a number with comma as decimal point to float Why does `\texttt` repeat and shrink my equation? When I use \texttt with the caret symbol in an amsmath equation environment, I get a very weird result. Specifically, the text repeats itself four times while shrinking.  MWE:  \documentclass{article} \usepackage{amsmath}  \begin{document}  \begin{equation*}     \texttt{y^o} \end{equation*}  \end{document}   Compiling this document with pdflatex produces the following result:    The same result occurs even if I remove the o character. To fix it I could modify the offending line to \texttt{y$^o$}, but why is this repeating happening in the first place? Err 80 appears when I turn on my Canon EOS 5D Mark II I want to resolve merge conflicts in my Git repository. How to do that ? Format a date in XML via XSLT Let $f$ be defined on $\mathbb{R}$ by $f(x) = e^{-1/x^2}$ for $x$ not equal to $0$. and $f(0)= 0$. Prove that $f^{(n)}(0)=0$ for all $n = 1, 2,3$ ...  Do I need to use Taylor expansion from calculus class?  Any hint would be appreciated. How can I determine whether a 2D Point is within a Polygon? Story about building up speed leading to increased quality of life I am interested in the situation where you have a very interesting result. For instance, you have solved a very important open problem. However, you are not known in the field and do not have any remarkable publications. Your supervisor thinks the work is good and you submit the work to a high profile journal, but you get rejected.  The thing is that the contribution is very strong. It breaks what most people believe or what they have already proven: e.g., you solve the P vs. NP problem or any other well known open problem.   The reviewers strongly reject your work with no justification and they do not state why the result is wrong. Examples of reviewer comments include:   "The proof must be wrong."  "You cannot achieve such a result."  "You do not understand well the notion of ..."   My question is what to do in this situation? Where to go? If your advisor accepts the work, but the reviewers from the top journal reject the work without even explaining the mistakes,  what should you do? Calendar.getInstance(TimeZone.getTimeZone("UTC")) is not returning UTC time How can I find the product key of Office 2011 after restoring from backup? I had to restore my iMac from a Time Machine backup.  Everything seemed fine until I tried to start Office 2011 and it is asking me to re-enter my product key. I am trying to locate my key (I believe I downloaded this version originally and it should be in my email but I can't find it)  I tried a program that is supposed to "find the keys for products installed on your computer" (Mac Product Key Finder) and it found my very old Office 2008 key, but not 2011.  I am surprised that if I had a totally working install before recovering from back-up that this wasn't restored as well - do I have any options to find it hiding somewhere on my drive?  Note: The recovery was after a hard drive was replaced by the Apple store - if that makes a difference, so this is a new internal drive. Creating a single index from several principal components or factors retained from PCA/FA I am using Principal Component Analysis (PCA) to create an index required for my research. My question is how I should create a single index by using the retained principal components calculated through PCA.  For instance, I decided to retain 3 principal components after using PCA and I computed scores for these 3 principal components. What is the appropriate ways to create, for each respondent, a single index out of these 3 scores?   Is it relevant to add the 3 computed scores to have a composite value? Or to average the 3 scores to have such a value?  Or should I just keep the first principal component (the strongest) only and use its score as the index?   Alternatively, one could use Factor Analysis (FA) but the same question remains: how to create a single index based on several factor scores? Why do some tag info pages show who created them and others don't? Some  show who created the tag:    while  don't. I'm pretty sure I created that one as well, if you hover over the timestamp you can see when it was created:    which more or less matches with  where I created the tag:    I understand that some tags like  were probably created by the Community user while the site itself was created (so it ), but some newer tags like   even though  still has an account here.  What's going on here? Would this also mean I wouldn't get a  for  if I ? Find the default application for a certain extension Given xdg-open and an extension, is there a way to get the application which xdg-open is set to for that particular extension?  For example given xdg-open and .jpg the result is eog. How do I change the extension of multiple files? I would like to change a file extension from *.txt to *.text. I tried using the basename command, but I'm having trouble on changing more than one file.  Here's my code:  files=`ls -1 *.txt`  for x in $files do     mv $x "`basename $files .txt`.text" done   I'm getting this error:  basename: too many arguments Try basename --help' for more information beamer - global transition shifts slide content Using beamer with the , I want to have a global transition effect (a fast fade) which I set using the following code:  \addtobeamertemplate{background canvas}{\transfade[duration=0.2]}{}   as found on  answer.  However, doing it messes up with my slides settings. It doesn't change every slides, only the \section ones that are slightly shifted to the right, adding a white line on the left, as seen here:   I tried using XeLaTeX and LuaLaTeX, as they are the only compilers I could use for my current font, but they both have the same issue.  It probably comes from the theme, however I have no clue why it would happen or how to fix it.  Edit :   \documentclass{beamer} \usetheme{m} \addtobeamertemplate{background canvas}{\transfade}{}  \begin{document} \section{test} \end{document}   Requires the mtheme to work Is there any way to do a correct word count of a LaTeX document? Often assignments (or even papers) have a word count limit. That is not a big deal when using Word, but I don't know how to do that using LaTeX. My solution has been so far to compile the document and then do a rough word count of my pdf file, sometimes even copying the contents of the pdf file and pasting in Word to get a mostly correct Word count.  Is there any tool (maybe even an online tool), package, script or software to do that directly from my .tex document and still get the right word count (i.e., ignore commands, equations, etc)?