19 lines
325 B
C++
19 lines
325 B
C++
#include <cmath>
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#include "nr.h"
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using namespace std;
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DP NR::factrl(const int n)
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{
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static int ntop=4;
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static DP a[33]={1.0,1.0,2.0,6.0,24.0};
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int j;
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if (n < 0) nrerror("Negative factorial in routine factrl");
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if (n > 32) return exp(gammln(n+1.0));
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while (ntop<n) {
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j=ntop++;
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a[ntop]=a[j]*ntop;
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}
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return a[n];
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}
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