/src/r-source/src/nmath/dgeom.c
Line | Count | Source |
1 | | /* |
2 | | * AUTHOR |
3 | | * Catherine Loader, catherine@research.bell-labs.com. |
4 | | * October 23, 2000. |
5 | | * |
6 | | * Merge in to R: |
7 | | * Copyright (C) 2000-2014 The R Core Team |
8 | | * |
9 | | * This program is free software; you can redistribute it and/or modify |
10 | | * it under the terms of the GNU General Public License as published by |
11 | | * the Free Software Foundation; either version 2 of the License, or |
12 | | * (at your option) any later version. |
13 | | * |
14 | | * This program is distributed in the hope that it will be useful, |
15 | | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
16 | | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
17 | | * GNU General Public License for more details. |
18 | | * |
19 | | * You should have received a copy of the GNU General Public License |
20 | | * along with this program; if not, a copy is available at |
21 | | * https://www.R-project.org/Licenses/ |
22 | | * |
23 | | * |
24 | | * DESCRIPTION |
25 | | * |
26 | | * Computes the geometric probabilities, Pr(X=x) = p(1-p)^x. |
27 | | */ |
28 | | |
29 | | #include "nmath.h" |
30 | | #include "dpq.h" |
31 | | |
32 | | double dgeom(double x, double p, int give_log) |
33 | 0 | { |
34 | 0 | #ifdef IEEE_754 |
35 | 0 | if (ISNAN(x) || ISNAN(p)) return x + p; |
36 | 0 | #endif |
37 | | |
38 | 0 | if (p <= 0 || p > 1) ML_WARN_return_NAN; |
39 | |
|
40 | 0 | R_D_nonint_check(x); |
41 | 0 | if (x < 0 || !R_FINITE(x) || p == 0) return R_D__0; |
42 | 0 | x = R_forceint(x); |
43 | | |
44 | | /* prob = (1-p)^x, stable for small p */ |
45 | 0 | double prob = dbinom_raw(0.,x, p,1-p, give_log); |
46 | |
|
47 | 0 | return((give_log) ? log(p) + prob : p*prob); |
48 | 0 | } |