I want to declare a self-referential structure as below         typedef struct     {             entry_t *entry;             node_t *next;     }node_t;   instead of as below for a linked-list    struct node   {          entry_t *entry;          struct node *next;   }*head;   does this work in C? If no why not?
How can I have a pointer to the next struct in the definition of this struct:  typedef struct A {   int a;   int b;   A*  next; } A;   this is how I first wrote it but it does not work.
Do you use "a" or "an" before acronyms / initialisms? Why is having a 2 stage flip-flop desirable? Are there advantages of having a master-slave compared to a one stage JK flip flop? Given $f = f(u(t), t)$, is it possible to find the following derivative? ($f$,$u \in \mathbb{R}^n$, $t \in \mathbb{R}$)  $$ \frac{\partial f}{\partial||u||^2_2} $$  I am aware of the following derivatives:  $$ \frac{\partial||x||^2_2}{\partial x} = \frac{\partial ||x^Tx||_2}{\partial x} = 2x $$  So I can invert it to give me (elementwise division in the RHS)  $$ \frac{\partial x}{\partial||x||^2_2} = \frac{1}{2x} $$  This step does feel like abuse of notation I find it hard to convince myself of its validity.  If it's right though, I could just apply the chain rule to find  $$ \frac{\partial f}{\partial u} \frac{\partial u}{\partial||u||^2_2} $$  However, knowing that both $f$ and $u$ are a function of $t$, I am somehow doubting my own reasoning. Or does that just mean that the derivative will still be a function of $t$ and I have nothing to worry about? Can anyone shed some light?  UPDATE: I'm now doubting the existence of  $$ \frac{\partial u}{\partial ||u||^2_2} $$  because $u = u(||u||_2^2)$ is not injective. Is the inversion step I did above legitimate? Is there another possible approach? Backup GNOME-Terminal Why do I have to solve for $x$ in this proof, if I choose not to find a counterexample? How to reduce vertical space in matrix? I want to reduce the size of the vertical space in matrix environment and have a result something like this     But at present I manage something like below     with the following code    $\begin{bmatrix}     00 &amp; 08 &amp; 10 &amp; 18 &amp; 20 &amp; 28 &amp; 30 &amp; 38 \\     01 &amp; 09 &amp; 11 &amp; 19 &amp; 21 &amp; 29 &amp; 31 &amp; 39 \\     02 &amp; 0a &amp; 12 &amp; 1a &amp; 22 &amp; 2a &amp; 32 &amp; 3a \\     03 &amp; 0b &amp; 13 &amp; 1b &amp; 23 &amp; 2b &amp; 33 &amp; 3b \\     04 &amp; 0c &amp; 14 &amp; 1c &amp; 24 &amp; 2c &amp; 34 &amp; 3c \\     05 &amp; 0d &amp; 15 &amp; 1d &amp; 25 &amp; 2d &amp; 35 &amp; 3d \\     06 &amp; 0e &amp; 16 &amp; 1e &amp; 26 &amp; 2e &amp; 36 &amp; 3e \\     07 &amp; 0f &amp; 17 &amp; 1f &amp; 27 &amp; 2f &amp; 37 &amp; 3f   \end{bmatrix}$   I can change the font using \mathsf{}, but other than that, how I reduce the vertical space between the rows? I did find things like  to increase vertical space between rows in matrix, but not something that can decrease the space. I am not very well versed on set theory or syntax, but I thought I knew the basics.  However, in a book about databases I am reading now, the author uses $2^x$ to signify "a set of $x$."  For example, $2^{\text{dogs}}$ is a set of $\text {dogs}$, etc.    The author never really explained this or why he does it, I just picked up the meaning from context.    I am not sure why the exponent operator is used, nor am I sure what the number $2$ has to do with it.  The sets being represented are NOT powers of $2$ (in size)... they come in all sizes.  Is this a valid notation?  I have not seen it anywhere before... Is there a correct resistance value for I2C pull-up resistors? What should i use for better performance, nine-patch or drawable xml resource? Console flashes on launching, then closes (ms-windows) How does someone get to cast more than 40 votes in a day? And by someone, I mean that evil feline WesleyDavid:        That screenshot was taken just before 4pm PST, i.e. just before 0000 UTC.  That shows KittehHead's votes for the month, which is the same as for the day since it's March 1st.  Just to be sure it wasn't that SE had the time wrong, I tried upvoting something and got the expected "Daily Vote Limit Reached, Please Vote Again in 6 minutes."  So how did Kitteh^H^H^H^H^H^HWesley get 42 votes in one day?  ADDED: It's getting worse... Now it's March 2nd, and Wesley/Cat has 3 extra votes:        Now I finally got an extra vote (take that evil kitteh!), but it hasn't helped me understand why: This problem is from a practice exam I was working on.     What is the cardinality of the quotient $\mathbb{Z}[x]/(x^2-3,2x+4)$ ?   Thoughts. If I find a ring that is easier to handle then this then I can go from there. So I think this is isomorphic to $\mathbb{Z}_2[x]/(x^2-3,x+2)$. And then I am stuck.  Am I correct so far? What should I be looking to do from here?  Thanks for your time and your answers. Proving a sequence converges by defining the sequence recursively. Let $a &gt; 0$. Choose $x_1 &gt;$ $\sqrt a$. Define a sequence {$x_n$} recursively as $x_{n+1} = 1/2(x_n + a/x_n)$ for $n &gt; 1$.   Prove that lim$x_n = \sqrt a$.  I think I first want to prove that {$x_n$} is bounded below by $\sqrt a$. But, I am having trouble with this. Could someone help me out a little? What fallacy dismisses problems by presenting "bigger" problems? Wasn't really sure how to phrase this, but I'm thinking of an instance in which someone diminishes a problem by presenting one of larger scope - as a rather shoddy example, "x political problem in America doesn't matter because half the world's population is starving."  I honestly have no idea if this is considered fallacious or not, but for some odd reason I can't shake the feeling that someone has described it to me as a fallacy before. Am I crazy or is there something to this (or something similar)? What's the best way to generate a tag cloud from an array using h1 through h6 for sizing? Group member cannot write even with write permission Difference between standard beta and unstandard beta distributions? Enable automatic deletion of old, unanswered, zero-score questions after a year? Related to Meta Super User efforts:  and Meta Server Fault efforts:  We already auto-remove negatively voted unanswered old questions automatically after 30 days, network wide, with no human intervention required. I was thinking we might extend that to remove old, unanswered zero score questions... based on the following criteria:  fewer than (question age in days * 1.5) views 0 score or lower, or 1 score or lower if the original author is deleted no answers 1 comment or fewer asked more than 1 year ago (thus based on creation date, not last activity date, so , or a user editing it, does not give a doomed question 365 more days of zombie &quot;life&quot;)  See the results of this query on:  (10509) |  (787) |  (650) This query has been refined based on the comments, and this is the final version that will roll out tonight. Every site in the network (except metas) will automatically delete old questions that meet this criteria from this point forward. Using url package without hyperref makes link hit boxes erratic I've currently got a url link in a footnote in my document. With the hyperref package, everything works correctly. Because the IEEE PDF Express tool doesn't like having the hyperref package, I've removed it and only left in the url package.  However, some strange behavior occurs as a result of this. Instead of just the link being clickable, entire paragraphs of text before/after end up being clickable and going to the same link. This occurs for both Skim and Preview in Mac OSX.  Does anyone have an inkling of what might be causing this? Read Post Data submitted to ASP.Net Form I have a working login form in an asp.net application.  Standard stuff with a username and password text box and a button to process the login.  Works fine.  I have a new requirement to allow the user to input the username and password from a separate plain html page that is not a part of my asp.net application.  I plan on achieving this using standard html - form, input, submit button etc.  The form action will be the URL of my asp.net login page and its method will be POST.    What I want to do in the C# code behind page of the asp.net login form, presumably in the Page_Load event, is to check if the request for the page contains a username and password value being passed in.  If it does then I need to read those values and process the login as if someone had clicked the login button on the asp.net page.  If not then I will display the login form as usual.    How do I check for the existence of, and read, the username and password values in the request for my page.