1 /*
2 * Mathlib : A C Library of Special Functions
3 * Copyright (C) 1998 Ross Ihaka
4 * Copyright (C) 2000-6 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 * http://www.r-project.org/Licenses/
20 *
21 * DESCRIPTION
22 *
23 * The distribution function of the binomial distribution.
24 */
25 #include "nmath.h"
26 #include "dpq.h"
27
pbinom(double x,double n,double p,int lower_tail,int log_p)28 double pbinom(double x, double n, double p, int lower_tail, int log_p)
29 {
30 #ifdef IEEE_754
31 if (ISNAN(x) || ISNAN(n) || ISNAN(p))
32 return x + n + p;
33 if (!R_FINITE(n) || !R_FINITE(p)) ML_ERR_return_NAN;
34
35 #endif
36 if(R_D_nonint(n)) ML_ERR_return_NAN;
37 n = R_D_forceint(n);
38 /* PR#8560: n=0 is a valid value */
39 if(n < 0 || p < 0 || p > 1) ML_ERR_return_NAN;
40
41 if (x < 0) return R_DT_0;
42 x = floor(x + 1e-7);
43 if (n <= x) return R_DT_1;
44 return pbeta(p, x + 1, n - x, !lower_tail, log_p);
45 }
46