33 lines
634 B
C++
33 lines
634 B
C++
#include "nr.h"
|
|
|
|
DP NR::ran1(int &idum)
|
|
{
|
|
const int IA=16807,IM=2147483647,IQ=127773,IR=2836,NTAB=32;
|
|
const int NDIV=(1+(IM-1)/NTAB);
|
|
const DP EPS=3.0e-16,AM=1.0/IM,RNMX=(1.0-EPS);
|
|
static int iy=0;
|
|
static Vec_INT iv(NTAB);
|
|
int j,k;
|
|
DP temp;
|
|
|
|
if (idum <= 0 || !iy) {
|
|
if (-idum < 1) idum=1;
|
|
else idum = -idum;
|
|
for (j=NTAB+7;j>=0;j--) {
|
|
k=idum/IQ;
|
|
idum=IA*(idum-k*IQ)-IR*k;
|
|
if (idum < 0) idum += IM;
|
|
if (j < NTAB) iv[j] = idum;
|
|
}
|
|
iy=iv[0];
|
|
}
|
|
k=idum/IQ;
|
|
idum=IA*(idum-k*IQ)-IR*k;
|
|
if (idum < 0) idum += IM;
|
|
j=iy/NDIV;
|
|
iy=iv[j];
|
|
iv[j] = idum;
|
|
if ((temp=AM*iy) > RNMX) return RNMX;
|
|
else return temp;
|
|
}
|