I have some code that I have to study and I'm not understanding what is a unsigned int and how it works.  void print_all_sums(unsigned int n,double a[n]) { // 1 &lt;= n &lt;= 30    unsigned int i,j,mask;    double s;   Something like this.
Am I correct to say the difference between a signed and unsigned integer is:  Unsigned can hold a larger positive value and no negative value. Unsigned uses the leading bit as a part of the value, while the signed version uses the left-most-bit to identify if the number is positive or negative. Signed integers can hold both positive and negative numbers.  Any other differences?
Mount cifs Network Drive: write permissions and chown I have access to a cifs network drive. When I mount it under my OSX machine, I can read and write from and to it.   When I mount the drive in ubuntu, using:  sudo mount -t cifs -o username=${USER},password=${PASSWORD} //server-address/folder /mount/path/on/ubuntu   I am not able to write to the network drive, but I can read from it. I have checked the permissions and owner of the mount folder, they look like:  4.0K drwxr-xr-x  4 root root    0 Nov 12  2010 Mounted_folder   I cannot change the owner, because I get the error:  chown: changing ownership of `/Volumes/Mounted_folder': Not a directory   When I descend deeper into the network drive, and change the ownership there, I get the error that I have no permission to change the folder´s owner.  What should I do to activate my write permission? Cycles in SHA-256 Let's say I start with a particular 256 bit value. Call this $v$. I then hash that value, and get another 256 bit value. Call this $\text{SHA256}(v)$. I take this value and get another 256 bit value. Call this $\text{SHA256}^2(v)$. More generally, let's call the result of hashing $v$ repeatedly $n$ times $\text{SHA256}^n(v)$.  Now my question is, how big will $n$ be, such that $\text{SHA256}^n(v) = v$?  It would seem to me, that if it's a giant sort of permutation, $n$ would have to be $2^{256}$, is that correct? Is that provable, or is there any information on this? (Just curiosity, really.)  Another question I had was, do all 256 bit strings have unique SHA256 values, and is there a way to show that? (Or, stated differently, can it be shown that there are no SHA-256 collisions in the language of all "256 bit strings"?) Can I travel to Dublin, Republic of Ireland with UK Tier 2/Schengen visas with Indian Passport Logistic regression cost surface not convex I am building a simple logistic regression model on 2D data. Here is the input I use.    I built a logistic regression model using this data and it successfully is able to find the discriminating line between these two classes. Here is the separating line found by my program:    Also, just for debugging, I plotted number of iterations vs J(theta), which also looks fine:    Now, confusing part comes into play. I am investigating the cost surface of this model that the logistic regressions is doing the gradient descent on. I am considering three different loss functions. Sum-of-squared loss, hinge-loss, log-loss.  Hinge loss:    Log-loss:    Sum-of-squared loss:    As far as I know, both hinge loss, sum-of-squared loss and log-loss should produce a convex surface. When I look at my surfaces, however, sum-of-squared surface does not look convex to me. Why is that the case?  For convenience, here is the two critical functions from my code:  function retval = J(X, y, theta)     M = size(y, 1);     % sum of squared error     retval = (1/(2*M)) * sum((h(X, theta) - y).^2);  endfunction  function retval = h (X, theta)     % logistic     retval =  1 ./ (1+ exp(-1 * (X * theta))); endfunction Is the function strcpy always dangerous? Java - when to use 'this' keyword There's something funky about some titles in revision histories here on Meta Stack Exchange How do I convert a hex string to an int in Python?   I may have it as "0xffff" or just "ffff". Blaise Pascal's famous wager was that even if the existence of God cannot be determined through reason, a rational person should wager as though God exists, because living life accordingly has everything to gain, and nothing to lose.  What logical flaws and/or fallacies (if any) are committed in making this argument? I have a filter using pre_get_posts to change the number of posts per page from 4 on the news landing page to 8 on all other pages (page 2, 3, etc). However I don't seem to have got the offset correct, or something, because my get_next_posts_page_link doesn't show a page 3, even though it does exist if I go to the url manually. The current offset is something I somehow managed to conjure up accidentally, I thought it worked as page 2 was correct but as I added more test posts, I realised it didn't work.  function page_2_posts_per_page_filter( $query ) {      $paged = (get_query_var('paged')) ? get_query_var('paged') : 1;      if ( !is_admin() &amp;&amp; $query-&gt;is_paged &amp;&amp; $query-&gt;is_main_query() ) {          $offset = 4 + (($paged - 2) * 8);         $query-&gt;set( 'offset', $offset );         $query-&gt;set( 'posts_per_page', 8 );      } else if (!is_admin() &amp;&amp; $query-&gt;is_main_query()) {          $query-&gt;set( 'posts_per_page', 4 );      }     return; } add_action( 'pre_get_posts', 'page_2_posts_per_page_filter', 1 );   EDIT: SOLUTION  function page_2_posts_per_page_filter( $query ) {      $paged = (get_query_var('paged')) ? get_query_var('paged') : 1;     $offset = 4;      if ( !is_admin() &amp;&amp; $query-&gt;is_paged &amp;&amp; $query-&gt;is_main_query() ) {          $offset = (($paged - 1) * 8) - $offset;         $query-&gt;set( 'posts_per_page', 8 );         $query-&gt;set( 'offset', $offset );      } else if (!is_admin() &amp;&amp; $query-&gt;is_main_query()) {          $query-&gt;set( 'posts_per_page', 4 );      }     return; } add_action( 'pre_get_posts', 'page_2_posts_per_page_filter');  function found_offset( $found_posts, $query ) {      $offset = 4;      if( !is_admin() &amp;&amp; $query-&gt;is_main_query() ) {         $found_posts = $found_posts + $offset;     }     return $found_posts; } add_action( 'found_posts', 'found_offset', 10, 2 ); Convert a list to a data frame Outlining in Blender? I am currently working on converting my logo vectored as a SVG to a 3D model using the 2.72 version. I ran into a problem with my logo because it contains a black stroke and an orange stroke (see both images below), but currently all I have is the interior color of each shape. I was wondering whether or not there was a simple way to add in these strokes, and how exactly to go about creating the strokes. Thank you in advance community! VBA Hide Rows that contain N/A How many keys does the Playfair Cipher have? Could someone give an example of a ‘very’ discontinuous derivative? I myself can only come up with examples where the derivative is discontinuous at only one point. I am assuming the function is real-valued and defined on a bounded interval. It is fine to say that for an object flying past a massive object, the spacetime is curved by the massive object, and so the object flying past follows the curved path of the geodesic, so it "appears" to be experiencing gravitational acceleration. Do we also say along with it, that the object flying past in reality exeriences NO attraction force towards the massive object? Is it just following the spacetime geodesic curve while experiencing NO attractive force?  Now come to the other issue: Supposing two objects are at rest relative to each other, ie they are not following any spacetime geodesic. Then why will they experience gravitational attraction towards each other? E.g. why will an apple fall to earth? Why won't it sit there in its original position high above the earth? How does the curvature of spacetime cause it to experience an attraction force towards the earth, and why would we need to exert a force in reverse direction to prevent it from falling? How does the curvature of spacetime cause this?  When the apple was detatched from the branch of the tree, it was stationary, so it did not have to follow any geodesic curve. So we cannot just say that it fell to earth because its geodesic curve passed through the earth. Why did the spacetime curvature cause it to start moving in the first place? $x_{1}...x_{n}$ are independent continuous random variables with common distribution function $F(x)$,consider the order statistics $(x_{(1)},...,x_{(n)})$, compute $E(F(x_{(n)})-F(x_{(1)}))$  I have no idea to this problem, anyone could help me? Thanks! If I run history, I can see my latest executed commands.  But if I do tail -f $HISTFILE or tail -f ~/.bash_history, they do not get listed.  Does the file get locked, is there a temporary location or something similar? Iterating each character in a string using Python Is there any way I can use  partitions on Windows&nbsp;7?  I have tried to install , but it doesn't seems to run on Windows&nbsp;7.