/* cdf/negbinom.c * * Copyright (C) 2004 Jason H. Stover. * * 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. */ #include #include #include #include #include /* * Pr(X <= n) for a negative binomial random variable X, i.e., * the probability of n or fewer failuers before success k. */ double gsl_cdf_negative_binomial_P(const long n, const long k, const double p) { double P; double a; double b; if(p > 1.0 || p < 0.0) { GSL_CDF_ERROR("p < 0 or p > 1",GSL_EDOM); } if ( k < 0 ) { GSL_CDF_ERROR ("k < 0",GSL_EDOM); } if ( n < 0 ) { P = 0.0; } else { a = (double) k; b = (double) n+1; P = gsl_cdf_beta_P(p, a, b); } return P; } /* * Pr ( X > n ). */ double gsl_cdf_negative_binomial_Q(const long n, const long k, const double p) { double P; double a; double b; if(p > 1.0 || p < 0.0) { GSL_CDF_ERROR("p < 0 or p > 1",GSL_EDOM); } if ( k < 0 ) { GSL_CDF_ERROR ("k < 0",GSL_EDOM); } if ( n < 0 ) { P = 1.0; } else { a = (double) k; b = (double) n+1; P = gsl_cdf_beta_Q(p, a, b); } return P; }