note 119430 added to function.mt-rand

rand() comes from the libc, and mt_rand() is internal to PHP. So the differences vary with their respective versions. On a 64b Debian Stretch with PHP 5.6.21, there is no visible difference: http://oi64.tinypic.com/2nkqas6.jpg This image compares the two functions. In the top half with random points, in the lower half with random intensity on each point. This is totally different from what was obtained 4 years ago in another note, with an unknown environment. Here is the code for this visual comparison. <?php $sizex = 400; $sizey = 400; $img = imagecreatetruecolor(2 * $sizex, 2 * $sizey); $white = imagecolorallocate($img, 255, 255, 255); $inks = array_map( function($r) use($img) { return imagecolorallocate($img, $r, $r, $r); }, range(0, 255) ); for ($x = 0 ; $x < $sizex ; $x++) { for ($y = 0 ; $y < $sizey ; $y++) { // placing ($sizex x $sizey) white points at random in the top half imagesetpixel($img, rand(0, $sizex - 1), rand(0, $sizey - 1), $white); imagesetpixel($img, $sizex + mt_rand(0, $sizex - 1), mt_rand(0, $sizey - 1), $white); // random intensity for each point in the lower half imagesetpixel($img, $x, $sizey + $y, $inks[rand(0, 255)]); imagesetpixel($img, $sizex + $x, $sizey + $y, $inks[mt_rand(0, 255)]); } } header("Content-type: image/png"); imagepng($img); ?> ---- Server IP: 72.52.91.14 Probable Submitter: 88.172.133.112 ---- Manual Page -- http://php.net/manual/en/function.mt-rand.php Edit -- https://master.php.net/note/edit/119430 Del: integrated -- https://master.php.net/note/delete/119430/integrated Del: useless -- https://master.php.net/note/delete/119430/useless Del: bad code -- https://master.php.net/note/delete/119430/bad+code Del: spam -- https://master.php.net/note/delete/119430/spam Del: non-english -- https://master.php.net/note/delete/119430/non-english Del: in docs -- https://master.php.net/note/delete/119430/in+docs Del: other reasons-- https://master.php.net/note/delete/119430 Reject -- https://master.php.net/note/reject/119430 Search -- https://master.php.net/manage/user-notes.php