Uh, if you mean a random value within a range:
function getRandomF(%lim0, %lim1)
{
%diff = %lim1 - %lim0;
return getRandom() * %diff + %lim0;
}
Note: The limits don't have to be in a specific order. getRandomF(20, -20); and getRandomF(-20, 20); return values in the same range.