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// -*- Mode: C++; tab-width: 2; -*-
// vi: set ts=2 sw=2
//
// $Id: randomNumberGenerator.C,v 1.1 2005/11/25 14:20:55 anker Exp $
//
#include <BALL/MATHS/randomNumberGenerator.h>
#include <BALL/common.h>
namespace BALL
{
RandomNumberGenerator::RandomNumberGenerator()
: valid_(false)
{
setup();
}
RandomNumberGenerator::RandomNumberGenerator(const RandomNumberGenerator&
rng)
: u_(rng.u_),
c_(rng.c_),
cd_(rng.cd_),
cm_(rng.cm_),
i97_(rng.i97_),
j97_(rng.j97_),
valid_(rng.valid_)
{
}
RandomNumberGenerator::~RandomNumberGenerator()
{
}
void RandomNumberGenerator::setup(int ij, int kl)
{
double s,t;
int ii,i,j,k,l,jj,m;
// allocate space for u_
u_.resize(97);
/*
Handle the seed range errors
First random number seed must be between 0 and 31328
Second seed must have a value between 0 and 30081
*/
if (ij < 0 || ij > 31328 || kl < 0 || kl > 30081)
{
Log.warn() << "Warning: Random number generator initialized with too large (ij > 31328 || kl > 30081) or negative values!\n" <<
" Using default values instead."<< std::endl;
ij = 1802;
kl = 9373;
}
i = (ij / 177) % 177 + 2;
j = (ij % 177) + 2;
k = (kl / 169) % 178 + 1;
l = (kl % 169);
for (ii=0; ii<97; ii++)
{
s = 0.0;
t = 0.5;
for (jj=0; jj<24; jj++)
{
m = (((i * j) % 179) * k) % 179;
i = j;
j = k;
k = m;
l = (53 * l + 1) % 169;
if (((l * m % 64)) >= 32)
s += t;
t *= 0.5;
}
u_[ii] = s;
}
c_ = 362436.0 / 16777216.0;
cd_ = 7654321.0 / 16777216.0;
cm_ = 16777213.0 / 16777216.0;
i97_ = 97;
j97_ = 33;
valid_ = true;
}
double RandomNumberGenerator::randomUniform()
{
if (!isValid())
{
Log.warn() << "RandomNumberGenerator::randomUniform(): "
<< "instance not valid, returning 0" << std::endl;
return(0.0);
}
double uni;
uni = u_[i97_-1] - u_[j97_-1];
if (uni <= 0.0) uni++;
u_[i97_-1] = uni;
i97_--;
if (i97_ == 0) i97_ = 97;
j97_--;
if (j97_ == 0) j97_ = 97;
c_ -= cd_;
if (c_ < 0.0) c_ += cm_;
uni -= c_;
if (uni < 0.0) uni++;
return(uni);
}
double RandomNumberGenerator::randomGaussian(double mean, double stddev)
{
double q,u,v,x,y;
/*
Generate P = (u,v) uniform in rect. enclosing acceptance region
Make sure that any random numbers <= 0 are rejected, since
gaussian() requires uniforms > 0, but RandomUniform() delivers >= 0.
*/
do {
u = randomUniform();
v = randomUniform();
if (u <= 0.0 || v <= 0.0)
{
u = 1.0;
v = 1.0;
}
v = 1.7156 * (v - 0.5);
/* Evaluate the quadratic form */
x = u - 0.449871;
y = fabs(v) + 0.386595;
q = x * x + y * (0.19600 * y - 0.25472 * x);
/* Accept P if inside inner ellipse */
if (q < 0.27597) break;
/* Reject P if outside outer ellipse, or outside acceptance region */
} while ((q > 0.27846) || (v * v > -4.0 * log(u) * u * u));
/* Return ratio of P's coordinates as the normal deviate */
return (mean + stddev * v / u);
}
int RandomNumberGenerator::randomInteger(int lower, int upper)
{
return((int)(randomUniform() * (upper - lower + 1)) + lower);
}
double RandomNumberGenerator::randomDouble(double lower, double upper)
{
return((upper - lower) * randomUniform() + lower);
}
}
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