3 * Copyright (C) 1996, 1997, 1998, 1999, 2000, 2007 James Theiler, Brian Gough
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 3 of the License, or (at
8 * your option) any later version.
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
22 #include <gsl/gsl_rng.h>
23 #include <gsl/gsl_randist.h>
25 /* The Pascal distribution is a negative binomial with valued integer n
27 prob(k) = (n - 1 + k)!/(n!(k - 1)!) * p^n (1-p)^k for k = 0, 1, ..., n
32 gsl_ran_pascal (const gsl_rng * r, double p, unsigned int n)
34 /* This is a separate interface for the pascal distribution so that
35 it can be optimized differently from the negative binomial in
38 e.g. if n < 10 it might be faster to generate the Pascal
39 distributions as the sum of geometric variates directly. */
41 unsigned int k = gsl_ran_negative_binomial (r, p, (double) n);
46 gsl_ran_pascal_pdf (const unsigned int k, const double p, unsigned int n)
48 double P = gsl_ran_negative_binomial_pdf (k, p, (double) n);