Gabriele Cosmo
102 lines
2.1 KiB
Plaintext
102 lines
2.1 KiB
Plaintext
// Copyright (C) 2010, Guy Barrand. All rights reserved.
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// See the file tools.license for terms.
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#ifndef tools_random
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#define tools_random
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#include <cstdlib> //::rand, RAND_MAX
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#include <cmath> //::sqrt, ::log
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#include "math"
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namespace tools {
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namespace random {
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class flat {
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public:
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double shoot() const {
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// Shoot random numbers in [0,1] according a flat distribution.
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double value = (double)::rand();
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value /= (double)RAND_MAX;
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return value;
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}
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};
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class gauss {
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public:
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gauss(double a_mean = 0,double a_std_dev = 1)
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:m_mean(a_mean),m_std_dev(a_std_dev){}
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public:
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gauss(const gauss& a_from)
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:m_mean(a_from.m_mean),m_std_dev(a_from.m_std_dev){}
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gauss& operator=(const gauss& a_from) {
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m_mean = a_from.m_mean;
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m_std_dev = a_from.m_std_dev;
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return *this;
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}
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public:
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double shoot() const {
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// Shoot random numbers according a
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// gaussian distribution of mean 0 and sigma 1.
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double v1,v2,r,fac;
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do {
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v1 = 2.0 * m_flat.shoot() - 1.0;
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v2 = 2.0 * m_flat.shoot() - 1.0;
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r = v1*v1 + v2*v2;
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} while ( r > 1.0 );
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fac = ::sqrt(-2.0*::log(r)/r);
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return (v2 * fac) * m_std_dev + m_mean;
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}
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private:
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flat m_flat;
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double m_mean;
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double m_std_dev;
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};
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class bw {
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public:
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bw(double a_mean = 0,double a_gamma = 1)
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:m_mean(a_mean),m_gamma(a_gamma){}
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public:
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bw(const bw& a_from)
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:m_mean(a_from.m_mean),m_gamma(a_from.m_gamma){}
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bw& operator=(const bw& a_from) {
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m_mean = a_from.m_mean;
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m_gamma = a_from.m_gamma;
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return *this;
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}
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public:
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double shoot() const {
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double rval = 2.0 * m_flat.shoot() - 1.0;
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double displ = 0.5 * m_gamma * ::tan(rval * half_pi());
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return m_mean + displ;
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}
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private:
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flat m_flat;
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double m_mean;
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double m_gamma;
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};
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class exp {
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public:
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exp(double a_rate = 1):m_rate(a_rate){}
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public:
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exp(const exp& a_from):m_rate(a_from.m_rate){}
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exp& operator=(const exp& a_from) {m_rate = a_from.m_rate;return *this;}
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public:
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double shoot() const {
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double v;
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do {
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v = m_flat.shoot();
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} while(v<=0);
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return -::log(v)/m_rate;
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}
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private:
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flat m_flat;
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double m_rate;
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};
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}}
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#endif
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