How to generate random +ve -ve decimal with php?

Question

how can I regenerate random decimal from -0.0010 to 0.0010 with php rand()? or any other?

Answer 1

.

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

Answer 2

This will return any possible number between -0.001 and +0.001

$random = ((rand()*(0.002/getrandmax()))-0.001)
// or without paranthesis:
$random = rand()*0.002/getrandmax()-0.001

Answer 3

Devide rand() by the maximum rand-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;
?>