/src/r-source/src/nmath/pgeom.c
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1 | | /* |
2 | | * Mathlib : A C Library of Special Functions |
3 | | * Copyright (C) 1998 Ross Ihaka |
4 | | * Copyright (C) 2000-2006 The R Core Team |
5 | | * Copyright (C) 2004 The R Foundation |
6 | | * |
7 | | * This program is free software; you can redistribute it and/or modify |
8 | | * it under the terms of the GNU General Public License as published by |
9 | | * the Free Software Foundation; either version 2 of the License, or |
10 | | * (at your option) any later version. |
11 | | * |
12 | | * This program is distributed in the hope that it will be useful, |
13 | | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
14 | | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
15 | | * GNU General Public License for more details. |
16 | | * |
17 | | * You should have received a copy of the GNU General Public License |
18 | | * along with this program; if not, a copy is available at |
19 | | * https://www.R-project.org/Licenses/ |
20 | | * |
21 | | * DESCRIPTION |
22 | | * |
23 | | * The distribution function of the geometric distribution. |
24 | | */ |
25 | | |
26 | | #include "nmath.h" |
27 | | #include "dpq.h" |
28 | | |
29 | | double pgeom(double x, double p, int lower_tail, int log_p) |
30 | 0 | { |
31 | 0 | #ifdef IEEE_754 |
32 | 0 | if (ISNAN(x) || ISNAN(p)) |
33 | 0 | return x + p; |
34 | 0 | #endif |
35 | 0 | if(p <= 0 || p > 1) ML_WARN_return_NAN; |
36 | |
|
37 | 0 | if (x < 0.) return R_DT_0; |
38 | 0 | if (!R_FINITE(x)) return R_DT_1; |
39 | 0 | x = floor(x +1e-7); |
40 | |
|
41 | 0 | if(p == 1.) { /* we cannot assume IEEE */ |
42 | 0 | x = lower_tail ? 1: 0; |
43 | 0 | return log_p ? log(x) : x; |
44 | 0 | } |
45 | 0 | x = log1p(-p) * (x + 1); |
46 | 0 | if (log_p) |
47 | 0 | return R_DT_Clog(x); |
48 | 0 | else |
49 | 0 | return lower_tail ? -expm1(x) : exp(x); |
50 | 0 | } |