How to generate a random positive or negative decimal?

Question

How can I regenerate random decimal from -0.0010 to 0.0010 with php rand() or some other method?

Answer 1

Divide rand() by the maximum random numer, multiply it by the range and add the starting number:

<?php
  // rand()/getrandmax() gives a float number between 0 and 1
  // if you multiply it by 0.002 you'll get a number between 0 and 0.002
  // add the starting number -0.001 and you'll get a number between -0.001 and 0.001

  echo rand()/getrandmax()*0.002-0.001;
?>

Answer 2

.

$val = (rand(0,20)-10)/10000;