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55 lines
878 B
C++
55 lines
878 B
C++
#ifndef RANDOM_NUMBER_GENERATORS_HPP
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#define RANDOM_NUMBER_GENERATORS_HPP
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#include <cmath>
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namespace RandomNumberGenerators {
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inline float uniform()
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/* Uniform random number generator x(n+1)= a*x(n) mod c
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with a = pow(7,5) and c = pow(2,31)-1.
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Copyright (c) Tao Pang 1997. */
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{
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const int ia=16807,ic=2147483647,iq=127773,ir=2836;
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int il,ih,it;
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float rc;
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static int iseed = rand();
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ih = iseed/iq;
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il = iseed%iq;
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it = ia*il-ir*ih;
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if (it > 0)
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{
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iseed = it;
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}
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else
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{
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iseed = ic+it;
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}
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rc = ic;
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return iseed/rc;
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}
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inline float gaussian(float mean, float sigma)
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{
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float x1, x2, w, y1, y2;
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do {
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x1 = 2.0 * uniform() - 1.0;
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x2 = 2.0 * uniform() - 1.0;
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w = x1 * x1 + x2 * x2;
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} while ( w >= 1.0 );
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w = sqrt( (-2.0 * log( w ) ) / w );
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y1 = x1 * w;
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y2 = x2 * w;
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float ret = y1*sigma + mean;
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return ret;
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}
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}
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#endif |