/* cdf/exponential.c *  * Copyright (C) 2003 Brian Gough *  * 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, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */#include <config.h>#include <math.h>#include <gsl/gsl_math.h>#include <gsl/gsl_cdf.h>/* The exponential distribution has the form   p(x) dx = exp(-x/mu) dx/mu   for x = 0 ... +infty */doublegsl_cdf_exponential_P (const double x, const double mu){  if (x < 0)    {      return 0;    }  else    {      double P = -expm1 (-x / mu);      return P;    }}doublegsl_cdf_exponential_Q (const double x, const double mu){  if (x < 0)    {      return 1;    }  else    {      double Q = exp (-x / mu);      return Q;    }}