/*

 *  Mathlib : A C Library of Special Functions

 *  Copyright (C) 1998 Ross Ihaka

 *  Copyright (C) 2000 The R Core Team

 *

 *  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/

 *

 *  DESCRIPTION

 *

 *    The density of the Cauchy distribution.

 */

#include "nmath.h"

#include "dpq.h"

double dcauchy(double x, double location, double scale, int give_log)

{

    double y;

#ifdef IEEE_754

    /* NaNs propagated correctly */

    if (ISNAN(x) || ISNAN(location) || ISNAN(scale))

  return x + location + scale;

#endif

    if (scale <= 0) ML_WARN_return_NAN;

    y = (x - location) / scale;

    return give_log ?

  - log(M_PI * scale * (1. + y * y)) :

  1. / (M_PI * scale * (1. + y * y));

}