| /* |
| * Mathlib : A C Library of Special Functions |
| * Copyright (C) 1998 Ross Ihaka |
| * Copyright (C) 2000-2016 The R Core Team |
| * |
| * 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, a copy is available at |
| * https://www.R-project.org/Licenses/ |
| * |
| * DESCRIPTION |
| * |
| * The distribution function of the negative binomial distribution. |
| * |
| * NOTES |
| * |
| * x = the number of failures before the n-th success |
| */ |
| |
| #include "nmath.h" |
| #include "dpq.h" |
| |
| double pnbinom(double x, double size, double prob, int lower_tail, int log_p) |
| { |
| #ifdef IEEE_754 |
| if (ISNAN(x) || ISNAN(size) || ISNAN(prob)) |
| return x + size + prob; |
| if(!R_FINITE(size) || !R_FINITE(prob)) ML_ERR_return_NAN; |
| #endif |
| if (size < 0 || prob <= 0 || prob > 1) ML_ERR_return_NAN; |
| |
| /* limiting case: point mass at zero */ |
| if (size == 0) |
| return (x >= 0) ? R_DT_1 : R_DT_0; |
| |
| if (x < 0) return R_DT_0; |
| if (!R_FINITE(x)) return R_DT_1; |
| x = floor(x + 1e-7); |
| return pbeta(prob, size, x + 1, lower_tail, log_p); |
| } |
| |
| double pnbinom_mu(double x, double size, double mu, int lower_tail, int log_p) |
| { |
| #ifdef IEEE_754 |
| if (ISNAN(x) || ISNAN(size) || ISNAN(mu)) |
| return x + size + mu; |
| if(!R_FINITE(mu)) ML_ERR_return_NAN; |
| #endif |
| if (size < 0 || mu < 0) ML_ERR_return_NAN; |
| |
| /* limiting case: point mass at zero */ |
| if (size == 0) |
| return (x >= 0) ? R_DT_1 : R_DT_0; |
| |
| if (x < 0) return R_DT_0; |
| if (!R_FINITE(x)) return R_DT_1; |
| if (!R_FINITE(size)) // limit case: Poisson |
| return(ppois(x, mu, lower_tail, log_p)); |
| |
| x = floor(x + 1e-7); |
| /* return |
| * pbeta(pr, size, x + 1, lower_tail, log_p); pr = size/(size + mu), 1-pr = mu/(size+mu) |
| * |
| *= pbeta_raw(pr, size, x + 1, lower_tail, log_p) |
| * x. pin qin |
| *= bratio (pin, qin, x., 1-x., &w, &wc, &ierr, log_p), and return w or wc .. |
| *= bratio (size, x+1, pr, 1-pr, &w, &wc, &ierr, log_p) */ |
| { |
| int ierr; |
| double w, wc; |
| bratio(size, x+1, size/(size+mu), mu/(size+mu), &w, &wc, &ierr, log_p); |
| if(ierr) |
| MATHLIB_WARNING(_("pnbinom_mu() -> bratio() gave error code %d"), ierr); |
| return lower_tail ? w : wc; |
| } |
| } |