| /* |
| * AUTHOR |
| * Catherine Loader, catherine@research.bell-labs.com. |
| * October 23, 2000. |
| * |
| * Merge in to R: |
| * Copyright (C) 2000-2014 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 |
| * |
| * Computes the geometric probabilities, Pr(X=x) = p(1-p)^x. |
| */ |
| |
| #include "nmath.h" |
| #include "dpq.h" |
| |
| double dgeom(double x, double p, int give_log) |
| { |
| double prob; |
| |
| #ifdef IEEE_754 |
| if (ISNAN(x) || ISNAN(p)) return x + p; |
| #endif |
| |
| if (p <= 0 || p > 1) ML_ERR_return_NAN; |
| |
| R_D_nonint_check(x); |
| if (x < 0 || !R_FINITE(x) || p == 0) return R_D__0; |
| x = R_forceint(x); |
| |
| /* prob = (1-p)^x, stable for small p */ |
| prob = dbinom_raw(0.,x, p,1-p, give_log); |
| |
| return((give_log) ? log(p) + prob : p*prob); |
| } |