#include "genlib.h"

#define IM1 2147483563
#define IM2 2147483399
#define AM (1.0/IM1)
#define IMM1 (IM1-1)
#define IA1 40014
#define IA2 40692
#define IQ1 53668
#define IQ2 52774
#define IR1 12211
#define IR2 3791
#define NTAB 32
#define NDIV (1+IMM1/NTAB)
#define EPS 1.2e-7
#define RNMX (1.0-EPS)

double ran2(long *idum, long *idum2, long *iy, long iv[NTAB])

{
  int j;
  long k;
  double temp;

  if (*idum <= 0) {
    if (-(*idum) < 1) *idum = 1;
    else *idum = -(*idum);
    *idum2 = (*idum);
    for (j = NTAB+7; j >= 0; j--) {
      k = (*idum)/IQ1;
      *idum = IA1*(*idum-k*IQ1)-k*IR1;
      if (*idum < 0) *idum += IM1;
      if (j < NTAB) iv[j] = *idum;
    }
    *iy = iv[0];
  }

  k = (*idum)/IQ1;
  *idum = IA1*(*idum-k*IQ1)-k*IR1;
  if (*idum < 0) *idum += IM1;
  k = *idum2/IQ2;
  *idum2 = IA2*(*idum2-k*IQ2)-k*IR2;
  if (*idum2 < 0) *idum2 += IM2;
  j = (*iy)/NDIV;
  *iy = iv[j]-(*idum2);
  iv[j] = *idum;
  if (*iy < 1) (*iy) += IMM1;
  if ((temp = AM*(*iy)) > RNMX) return (RNMX);
  else return (temp);
}