27 lines
408 B
C
27 lines
408 B
C
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#include <math.h>
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float gasdev(long *idum)
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{
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float ran1(long *idum);
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static int iset=0;
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static float gset;
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float fac,rsq,v1,v2;
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if (*idum < 0) iset=0;
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if (iset == 0) {
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do {
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v1=2.0*ran1(idum)-1.0;
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v2=2.0*ran1(idum)-1.0;
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rsq=v1*v1+v2*v2;
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} while (rsq >= 1.0 || rsq == 0.0);
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fac=sqrt(-2.0*log(rsq)/rsq);
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gset=v1*fac;
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iset=1;
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return v2*fac;
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} else {
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iset=0;
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return gset;
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}
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}
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