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add numerical recipes library

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yenru0
2025-09-12 18:55:25 +09:00
parent d4dff245bd
commit 2c75620ec9
1344 changed files with 63869 additions and 0 deletions
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38
lib/nr/cpp/recipes/ran2.cpp Normal file
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#include "nr.h"
DP NR::ran2(int &idum)
{
const int IM1=2147483563,IM2=2147483399;
const int IA1=40014,IA2=40692,IQ1=53668,IQ2=52774;
const int IR1=12211,IR2=3791,NTAB=32,IMM1=IM1-1;
const int NDIV=1+IMM1/NTAB;
const DP EPS=3.0e-16,RNMX=1.0-EPS,AM=1.0/DP(IM1);
static int idum2=123456789,iy=0;
static Vec_INT iv(NTAB);
int j,k;
DP temp;
if (idum <= 0) {
idum=(idum==0 ? 1 : -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;
}