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34 lines
866 B
C
34 lines
866 B
C
#include "genlib.h"
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#include <math.h>
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#include <time.h>
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#define NTAB 32
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double gasdev(long* idum, long* idum2, long* iy, long iv[NTAB]) {
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/*returns a normally distributed deviate with 0 mean*/
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/*and unit variance, using ran2(idum) as the source */
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/*of uniform deviates */
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double ran2(long* idum, long* idum2, long* iy, long iv[NTAB]);
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static int iset = 0;
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static double gset;
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double fac, rsq, v1, v2;
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if (iset == 0) {
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do {
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v1 = 2.0 * ran2(idum, idum2, iy, iv) - 1.0;
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v2 = 2.0 * ran2(idum, idum2, iy, iv) - 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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