Pasted

/* double random_normal(mean, standard_deviation);
* Implements the Polar form of the Box-Muller Transformation
*
* © Copyright 1994, Everett F. Carter Jr.
* Ported to GML by Tsa05
* Slightly modified by Dragonite (Dimenticare on Pastebin)
* Permission is granted by the author to use
* this software for any application provided this
* copyright notice is preserved.
* 
* Recall that numbers beyond the Standard Deviation
* are possible (just not probable), and should be accounted for.
*
*/
 
var m, s;
 
m=argument0;
s=argument1;
 
var x1, x2, w, y1;
 
w=2;
 
while ( w >= 1.0 ){
    x1 = 2.0 * random(1) - 1.0; 
    x2 = 2.0 * random(1) - 1.0; 
    w = x1 * x1 + x2 * x2; 
}
 
var r;
r=m+(x1*(sqrt((-2.0*ln(w))/w)))*s;
if (r>0)
    return r;
return random_normal(argument0, argument1);