/* uniform [0,1] random number generator
   developed by Pierre Lecuyer based on a clever
   and tested combination of two linear congruential
   sequences 
*/

/*
s1 and s2 are the seeds (nonnegative integers)
*/

#include <math.h>

double uni()
{
static long s1 = 55555;
static long s2 = 99999;
static double factor = 1.0/2147483563.0;
register long k,z;
	k= s1 /53668;
	s1 =40014*(s1%53668)-k*12211;
	if (s1 < 0) s1 += 2147483563;
	k=s2/52774;
	s2=40692*(s2%52774)-k*3791;
	if (s2 < 0) s2 += 2147483399;

	/*
	z = abs(s1 ^ s2);
	*/
	z= (s1 - 2147483563) + s2;
	if (z < 1) z += 2147483562;
	
	return(((double)(z))*factor);
}