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/* -*- c++ -*- */
/*
* Copyright 2002 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* GNU Radio is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3, or (at your option)
* any later version.
*
* GNU Radio is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Radio; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
/*
* Copyright 1997 Massachusetts Institute of Technology
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation, and that the name of M.I.T. not be used in advertising or
* publicity pertaining to distribution of the software without specific,
* written prior permission. M.I.T. makes no representations about the
* suitability of this software for any purpose. It is provided "as is"
* without express or implied warranty.
*
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <math.h>
#include <gnuradio/random.h>
namespace gr {
random::random(unsigned int seed)
{
d_gauss_stored = false; // set gasdev (gauss distributed numbers) on calculation state
// Setup random number generator
d_rng = new boost::mt19937;
reseed(seed); // set seed for random number generator
d_uniform = new boost::uniform_real<float>;
d_generator = new boost::variate_generator<boost::mt19937&, boost::uniform_real<float> > (*d_rng,*d_uniform); // create number generator in [0,1) from boost.random
}
random::~random()
{
delete d_rng;
delete d_uniform;
delete d_generator;
}
/*
* Seed is initialized with time if the given seed is 0. Otherwise the seed is taken directly. Sets the seed for the random number generator.
*/
void
random::reseed(unsigned int seed)
{
if(seed==0) d_seed = static_cast<unsigned int>(std::time(0)); // FIXME: add seed method correctly
else d_seed = seed;
d_rng->seed(d_seed);
}
/*
* Returns uniformly distributed numbers in [0,1) taken from boost.random using a Mersenne twister
*/
float
random::ran1()
{
return (*d_generator)();
}
/*
* Returns a normally distributed deviate with zero mean and variance 1.
* Used is the Marsaglia polar method.
* Every second call a number is stored because the transformation works only in pairs. Otherwise half calculation is thrown away.
*/
float
random::gasdev()
{
if(d_gauss_stored){ // just return the stored value if available
d_gauss_stored = false;
return d_gauss_value;
}
else{ // generate a pair of gaussian distributed numbers
float x,y,s;
do{
x = 2.0*ran1()-1.0;
y = 2.0*ran1()-1.0;
s = x*x+y*y;
}while(not(s<1.0));
d_gauss_stored = true;
d_gauss_value = x*sqrt(-2.0*log(s)/s);
return y*sqrt(-2.0*log(s)/s);
}
}
float
random::laplacian()
{
float z = ran1()-0.5;
if(z>0) return -log(1-2*z);
else return log(1+2*z);
}
/*
* Copied from The KC7WW / OH2BNS Channel Simulator
* FIXME Need to check how good this is at some point
*/
// 5 => scratchy, 8 => Geiger
float
random::impulse(float factor = 5)
{
float z = -M_SQRT2 * log(ran1());
if(fabsf(z) <= factor)
return 0.0;
else
return z;
}
gr_complex
random::rayleigh_complex()
{
return gr_complex(gasdev(),gasdev());
}
float
random::rayleigh()
{
return sqrt(-2.0 * log(ran1()));
}
} /* namespace gr */
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