ID: 37528
User updated by: lunter at interia dot pl
Reported By: lunter at interia dot pl
Status: Bogus
Bug Type: Math related
Operating System: WinXP
PHP Version: 5.1.4
New Comment:
Ok.... maybe system dependent ... but MatLab rand() generate perfect
noise on WinXP.
Previous Comments:
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[2006-05-19 20:54:46] [EMAIL PROTECTED]
They are system dependent, it is not a php problem. Now please keep
this bug as bogus and read the manual.
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[2006-05-19 20:49:31] lunter at interia dot pl
Sorry but..
run this script on Linux PHP - perfect noise
run this script on WinXP PHP - pattern!
WinXP rand() should be good like Linux rand()
Actually rand() is not the same.
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[2006-05-19 20:37:37] [EMAIL PROTECTED]
Use mt_rand if you want better random values.
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[2006-05-19 20:35:01] lunter at interia dot pl
e.g. MatLab rand() generate perfect noise.
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[2006-05-19 20:26:41] lunter at interia dot pl
Description:
------------
rand() weakness.
example (reproduce code): rand generate pattern instead of noise
Reproduce code:
---------------
<?
$i=imagecreatetruecolor(1024,768);
for($y=0;$y<768;$y++){
for($x=0;$x<1024;$x++){
$c=rand(0,1)*255;
imagesetpixel($i,$x,$y,($c<<16)+($c<<8)+$c);
}
}
header('Content-type: image/png');
imagepng($i);
?>
Expected result:
----------------
noise
Actual result:
--------------
pattern
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Edit this bug report at http://bugs.php.net/?id=37528&edit=1
