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Paste ID: # mwLQY
Date posted: Wed, 18 Jan 2012 22:26:01 +0000
Date of expiration: never (permanent entry)
Description:

(PHP) Generate / Create (pseudo) random numbers between -1 and 1

  1. <?php
  2. /**To generate (pseudo) random numbers in range of -1 and 1 you can use the cosine
  3.  * that will return a number in range of -1.0 and 1.0.
  4.  *
  5.  * Note for nerds:
  6.  * It's not a real big problem that the cosine is deterministic due to the fact that mt_rand isn't really perfect, too. Hence this is PSEUDO random number generation.
  7.  */
  8. $r = cos( mt_rand() );
  9.  
  10. // In case your mt_rand() implementation returns (for whatever reason) values between 0.0 and 1.0 go with:
  11. $r = cos( mt_rand() );
  12. if( intval( mt_rand() ) % 2 == 0 ) // Switch sign randomly
  13.   $r = -$r;
  14. ?>
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