ran1.txt

教你怎么用C++产各种各样的随机数

#include<iostream.h>
static double r[98];
static int iff,ix1,ix2,ix3;
double ran1(int &idum)
{
  double rm1,rm2,t;
  int m1,m2,m3,ia1,ia2,ia3,ic1,ic2,ic3,j;
  m1=2592000,ia1=7141,ic1=54773,rm1=0.0000038580247;
  m2=134456,ia2=8121,ic2=28411,rm2=0.0000074373773;
  m3=243000,ia3=4561,ic3=51349;
  if((idum<0)||(idum==0))
  {
    iff=1;
    ix1=(ic1-idum)%m1;
    ix1=(ia1*ix1+ic1)%m1;
    ix2=ix1%m2;
    ix1=(ia1*ix1+ic1)%m1;
    ix3=ix1%m3;
    for(j=1;j<=97;j++)
    {
      ix1=(ia1*ix1+ic1)%m1;
      ix2=(ia2*ix2+ic2)%m2;
     r[j]=(double (ix1)*double (ix2)*rm2)*rm1;
    }
    idum=1;
  }
   ix1=(ia1*ix1+ic1)%m1;
   ix2=(ia2*ix2+ic2)%m2;
   ix3=(ia3*ix3+ic3)%m3;
   if((j>97)||(j<1))
   {
     cout<<"abnormal exit"}<<endl;
     return 1;
       }
   t=r[j];
   r[j]=(float (ix1)+float (ix2)*rm2)*rm1;
   return t;
}