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/* ---------------------------- rand_beta ----------------------------------- */
/* */
/* rand_beta generates a beta distributed random variable. */
/* Written by Olaf Matthes (olaf.matthes@gmx.de) */
/* Based on code found in Dodge/Jerse "Computer Music" */
/* Get source at http://www.akustische-kunst.org/puredata/maxlib/ */
/* */
/* This program 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 2 */
/* of the License, or (at your option) any later version. */
/* */
/* This program 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 this program; if not, write to the Free Software */
/* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
/* */
/* Based on PureData by Miller Puckette and others. */
/* */
/* ---------------------------------------------------------------------------- */
#include "m_pd.h"
#include <stdlib.h>
#include <time.h>
#include <math.h>
#define fran() (t_float)rand()/(t_float)RAND_MAX
#ifndef M_PI
#define M_PI 3.1415927
#endif
static char *version = "beta v0.1, generates a beta distributed random variable\n"
" written by Olaf Matthes <olaf.matthes@gmx.de>";
/* -------------------------- rand_beta ------------------------------ */
static t_class *rand_beta_class;
typedef struct _rand_beta
{
t_object x_obj;
t_float x_a;
t_float x_b;
} t_rand_beta;
static void *rand_beta_new(t_floatarg a, t_floatarg b)
{
t_rand_beta *x = (t_rand_beta *)pd_new(rand_beta_class);
srand( (unsigned)time( NULL ) );
floatinlet_new(&x->x_obj, &x->x_a);
floatinlet_new(&x->x_obj, &x->x_b);
outlet_new(&x->x_obj, &s_float);
x->x_a = a;
x->x_b = b;
return (x);
}
static void rand_beta_bang(t_rand_beta *x)
{
t_float u1, u2, y1, y2, sum, a, b, ainv, binv;
a = (x->x_a <= 0 ? 0.0001 : x->x_a);
b = (x->x_b <= 0 ? 0.0001 : x->x_b);
ainv = 1/a;
binv = 1/b;
do
{
do
{
u1 = fran();
}
while(u1 == 0);
do
{
u2 = fran();
}
while(u2 == 0);
y1 = pow(u1, ainv);
y2 = pow(u2, binv);
sum = y1 + y2;
}
while(sum > 1);
outlet_float(x->x_obj.ob_outlet, y1/sum);
}
void beta_setup(void)
{
rand_beta_class = class_new(gensym("beta"), (t_newmethod)rand_beta_new, 0,
sizeof(t_rand_beta), 0, A_DEFFLOAT, A_DEFFLOAT, 0);
class_addbang(rand_beta_class, rand_beta_bang);
class_sethelpsymbol(rand_beta_class, gensym("maxlib/help-beta.pd"));
#ifndef MAXLIB
post(version);
#endif
}
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