| /* |
| * R : A Computer Language for Statistical Data Analysis |
| * Copyright (C) 1995, 1996 Robert Gentleman and Ross Ihaka |
| * Copyright (C) 2000 The R Core Team |
| * Copyright (C) 2005 The R Foundation |
| * |
| * 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/ |
| */ |
| |
| #include "nmath.h" |
| #include "dpq.h" |
| |
| double qlogis(double p, double location, double scale, int lower_tail, int log_p) |
| { |
| #ifdef IEEE_754 |
| if (ISNAN(p) || ISNAN(location) || ISNAN(scale)) |
| return p + location + scale; |
| #endif |
| R_Q_P01_boundaries(p, ML_NEGINF, ML_POSINF); |
| |
| if (scale < 0.) ML_ERR_return_NAN; |
| if (scale == 0.) return location; |
| |
| /* p := logit(p) = log( p / (1-p) ) : */ |
| if(log_p) { |
| if(lower_tail) |
| p = p - R_Log1_Exp(p); |
| else |
| p = R_Log1_Exp(p) - p; |
| } |
| else |
| p = log(lower_tail ? (p / (1. - p)) : ((1. - p) / p)); |
| |
| return location + scale * p; |
| } |