I see following code in a script:  OLD_IFS="$IFS" IFS='something-special' # code that needs the special IFS # ... IFS="$OLD_IFS"   If the IFS is not set before the script fragment then the script sets it to an empty string and the empty IFS and undefined IFS are different.  The script probably assume the IFS is always set. Is it safe to make such assumption?
I am always really hesitant to mess around with $IFS because it's clobbering a global.   But often it makes loading strings into a bash array nice and concise, and for bash scripting, conciseness is hard to come by.   So I figure it might be better than nothing if I try to "save" the starting contents of $IFS to another variable and then restore it immediately after i am done using $IFS for something.   Is this practical? Or is it essentially pointless and I should just directly set IFS back to whatever it needs to be for its subsequent uses?
Why doesn't [Required] work for me? MVC3 Cloth collision with an object I know this is a really basic question, but I've just started with some basic C++ programming after coding a few projects with high-level languages.   Basically I have three questions:   Why use pointers over normal variables? When and where should I use pointers? How do you use pointers with arrays? \@seccntformat only for section I would like to add a dot between the number of the section and section name. I used   \makeatletter \renewcommand*{\@seccntformat}[1]{% \csname the#1\endcsname .} \makeatother   The problem is that, obviously, it put a dot also among subsection number and subsection name which I do not want. Is it possible to add the dot only between section number and section using low level instructions i.e. without any additional package? Explanation of terminal objects using limits I understand terminal objects, but I falter when trying to achieve them using the approach of diagrams, the category of constant diagrams $\mathcal{C}^{\mathcal{J}}$ and limits.  I have the empty category 0, now I have a diagram $D: \mathcal{J} \to \mathcal{C}$. However this diagrams image should be empty, because there are no objects or morphisms to map. At this point, I'm confused, because I can't get to the universal property $\forall c \in \mathcal{C}. \exists! f: c \to T$ anymore, because I'm missing T. (EDIT: I get that this is how it is supposed to be)  But continuing with the category of constant diagrams, even if I have a constant diagram mapping everything to one object / morphism, there is nothing to map, so the functors image is still empty. So now I'm missing both $T$, and any kind of $c$.  EDIT: It seems to me, have I chosen 1, instead of 0, I would have come up with that is considered the definition of the terminal category. What am I missing? How do I find the location of Python module sources? How do I learn where the source file for a given Python module is installed? Is the method different on Windows than on Linux?  I'm trying to look for the source of the datetime module in particular, but I'm interested in a more general answer as well. What is the easiest way to find and replace text in 20 text files in a directory? I have 20 text files with various extensions in a directory.  I want to replace "nnn" with "ooo" in all files.  I could import them into a project in Eclipse or Visual Studio to replace them all but that is overkill and would add other meta files etc.  What is a simple way to do this, I'm thinking: select all files, right click, choose some tool called (e.g. "QuickReplacer") and fill in find and replace, click and done.  Does anyone know of a tool like this? Background: One of my co-authors faced problem of compiling the paper that I had built using TexStudio and MikteX 2.9 on his Mac Machine running TexLive.   ShareLaTeX Role: So, one solution is to use ShareLaTeX. But the first problem pops in mind is how safe is uploading unpublished article to a publicly accessible portal?  What I did: I googled security and data breach of ShareLaTex and found nothing except some words from the ShareLaTex community about their word to ensure that our data are safe; perhaps this would not be enough.  My 1st Question: To what extent can I trust ShareLaTeX and put my ready-to-publish content there?   My 2nd Question: Is there any alternate way of sharing LaTeX with others around the globe without changing the underlying platform? If every eigenvector of $T$ is also an eigenvector of $T^{*}$ then $T$ is a normal operator Let $V$ be a finite-dimensional inner product space over $\mathbb{C}$ and $T: V \to V$ a linear transformation.   Show that if every eigenvector of $T$ is also an eigenvector of $T^{*}$ then $T$ is a normal.   We need to show that $\forall v \in V,\ TT^*v=T^*Tv$.  I started by picking $v$ to be an eigenvector of $T$, hence $Tv=\lambda_1 v$, and $T^*v=\lambda_2 v$. Therefore: $$TT^*v=T(\lambda_2 v)=\lambda_2 Tv=\lambda_1 \lambda_2 v=...=T^*Tv$$  But I'm stuck when $v$ is not an eigenvector.  (Also, this question is taken from a chapter about Jordan forms, but I can't see how it relates) Panasonic Eneloop BK-3MCC (4th gen) - where I can find maximum discharge current? Im looking for some official information source about maximum current for Panasonic Eneloop BK-3MCC rechargeable batteries.  All I found is , there is just 1 table (nothing about maximum discharge current), charge and discharge characteristics.  UPDATE LINK:   / edited - I fixed my mistake, I meant 6A not 8A /  There is discharge characteristic for 6000mA discharge. So... I can safely draw 6A from that AA cell? How old should you be when you begin Jedi training? In Star Trek, does the original die in teleportation? I am just curious.  If I am teleported is the original me dead and the teleporter just makes another copy of me there[at destination]? There does not exist an entire function which satisfies $f({1\over n})={1\over 2^n}$? There does not exist an entire function which satisfies $f({1\over n})={1\over 2^n}$, what I tried is if possible then define $g(z)=f(z)-{1\over 2^{1\over z}}$ Then $g({1\over n})=0$ and so $g(z)$ is entire and its $0$ set has limit point in it and so $f(z)={1\over 2^{1\over z}}$ which is not analytic at $0$? Please help!  Edit: OOps! the way I defined $g(z)$ that is not entire! could any one give me hint? How to look up a symbol or identify a letter from a math alphabet or other character? I know what my symbol or character looks like, but I don't know what the command is or which math alphabet it came from. How do I go about finding this out? Can't operator == be applied to generic types in C#? According to the documentation of the == operator in ,      For predefined value types, the   equality operator (==) returns true if   the values of its operands are equal,   false otherwise. For reference types   other than string, == returns true if   its two operands refer to the same   object. For the string type, ==   compares the values of the strings.   User-defined value types can overload   the == operator (see operator). So can   user-defined reference types, although   by default == behaves as described   above for both predefined and   user-defined reference types.   So why does this code snippet fail to compile?  bool Compare&lt;T&gt;(T x, T y) { return x == y; }   I get the error Operator '==' cannot be applied to operands of type 'T' and 'T'. I wonder why, since as far as I understand the == operator is predefined for all types?  Edit: Thanks, everybody. I didn't notice at first that the statement was about reference types only. I also thought that bit-by-bit comparison is provided for all value types, which I now know is not correct.  But, in case I'm using a reference type, would the == operator use the predefined reference comparison, or would it use the overloaded version of the operator if a type defined one?  Edit 2: Through trial and error, we learned that the == operator will use the predefined reference comparison when using an unrestricted generic type. Actually, the compiler will use the best method it can find for the restricted type argument, but will look no further. For example, the code below will always print true, even when Test.test&lt;B&gt;(new B(), new B()) is called:  class A { public static bool operator==(A x, A y) { return true; } } class B : A { public static bool operator==(B x, B y) { return false; } } class Test { void test&lt;T&gt;(T a, T b) where T : A { Console.WriteLine(a == b); } } Schwarz's Lemma, fixed points question This is from an old qualifying examination question.  If f is holomorphic in the unit disk $D$ and $|f(z)|&lt;1$ for all $z\in D$. Suppose also that $f$ has two distinct fixed points in $D$ then $f(z)=z$ for every $z\in D$  I know that I have to use the Schwarz's lemma and may be make use of Möbius transformations. I tried setting $g(z)=\phi_a\circ f\circ \phi_{-a}$. But that does not seem to work because I don't see why $|g(z)|=|z|$ for some non zero $z$.   Any helpful hints are greatly appreciated.  Edit: Of course the $a$ above is one of the fixed points. How can I send an email using a template? I have created a email template in ExactTarget API and I want to use it executing XML from SoapUI.  Is there any tutorial or examples of how can this be done?  I'm new at this and I'm not sure how ExactTarget really works. Quicksort vs heapsort Hyperref: Changing the linkcolor locally in the TOC I found that the link-color for TOC text is identical to the link-color for Figures and Tables. When I change the color to black in the TOC also the color for Figures/Tables citation etc. is changed.  Is there a way to separately set the colors inside the TOC and outside? Integral of periodic function over the length of the period is the same everywhere