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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.
*
*/
#include <math.h>
#include <gr_random.h>
#define IA 16807
#define IM 2147483647
#define AM (1.0/IM)
#define IQ 127773
#define IR 2836
#define NDIV (1+(IM-1)/NTAB)
#define EPS 1.2e-7
#define RNMX (1.0-EPS)
gr_random::gr_random (long seed)
{
reseed (seed);
}
void
gr_random::reseed (long seed)
{
d_seed = seed;
d_iy = 0;
for (int i = 0; i < NTAB; i++)
d_iv[i] = 0;
d_iset = 0;
d_gset = 0;
}
/*
* This looks like it returns a uniform random deviate between 0.0 and 1.0
* It looks similar to code from "Numerical Recipes in C".
*/
float gr_random::ran1()
{
int j;
long k;
float temp;
if (d_seed <= 0 || !d_iy) {
if (-d_seed < 1)
d_seed=1;
else
d_seed = -d_seed;
for (j=NTAB+7;j>=0;j--) {
k=d_seed/IQ;
d_seed=IA*(d_seed-k*IQ)-IR*k;
if (d_seed < 0)
d_seed += IM;
if (j < NTAB)
d_iv[j] = d_seed;
}
d_iy=d_iv[0];
}
k=(d_seed)/IQ;
d_seed=IA*(d_seed-k*IQ)-IR*k;
if (d_seed < 0)
d_seed += IM;
j=d_iy/NDIV;
d_iy=d_iv[j];
d_iv[j] = d_seed;
temp=AM * d_iy;
if (temp > RNMX)
temp = RNMX;
return temp;
}
/*
* Returns a normally distributed deviate with zero mean and variance 1.
* Also looks like it's from "Numerical Recipes in C".
*/
float gr_random::gasdev()
{
float fac,rsq,v1,v2;
d_iset = 1 - d_iset;
if (d_iset) {
do {
v1=2.0*ran1()-1.0;
v2=2.0*ran1()-1.0;
rsq=v1*v1+v2*v2;
} while (rsq >= 1.0 || rsq == 0.0);
fac= sqrt(-2.0*log(rsq)/rsq);
d_gset=v1*fac;
return v2*fac;
}
return d_gset;
}
/*
* Copied from The KC7WW / OH2BNS Channel Simulator
* FIXME Need to check how good this is at some point
*/
float gr_random::laplacian()
{
float z = ran1();
if (z < 0.5)
return log(2.0 * z) / M_SQRT2;
else
return -log(2.0 * (1.0 - z)) / M_SQRT2;
}
/*
* Copied from The KC7WW / OH2BNS Channel Simulator
* FIXME Need to check how good this is at some point
*/
// 5 => scratchy, 8 => Geiger
float gr_random::impulse(float factor = 5)
{
float z = -M_SQRT2 * log(ran1());
if (fabsf(z) <= factor)
return 0.0;
else
return z;
}
/*
* Complex rayleigh is really gaussian I and gaussian Q
* It can also be generated by real rayleigh magnitude and
* uniform random angle
* Adapted from The KC7WW / OH2BNS Channel Simulator
* FIXME Need to check how good this is at some point
*/
gr_complex gr_random::rayleigh_complex()
{
return gr_complex(gasdev(),gasdev());
}
/* Other option
mag = rayleigh();
ang = 2.0 * M_PI * RNG();
*Rx = rxx * cos(z);
*Iy = rxx * sin(z);
*/
float gr_random::rayleigh()
{
return sqrt(-2.0 * log(ran1()));
}
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