/* Copyright (C) 2015 Atsushi Togo */
/* All rights reserved. */

/* This file is part of phonopy. */

/* Redistribution and use in source and binary forms, with or without */
/* modification, are permitted provided that the following conditions */
/* are met: */

/* * Redistributions of source code must retain the above copyright */
/*   notice, this list of conditions and the following disclaimer. */

/* * Redistributions in binary form must reproduce the above copyright */
/*   notice, this list of conditions and the following disclaimer in */
/*   the documentation and/or other materials provided with the */
/*   distribution. */

/* * Neither the name of the phonopy project nor the names of its */
/*   contributors may be used to endorse or promote products derived */
/*   from this software without specific prior written permission. */

/* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS */
/* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT */
/* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS */
/* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE */
/* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, */
/* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, */
/* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; */
/* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER */
/* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT */
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/* POSSIBILITY OF SUCH DAMAGE. */

#include "phonoc_utils.h"

#include <math.h>

#include "phonoc_const.h"

#define THZTOEVPARKB 47.992398658977166
#define INVSQRT2PI 0.3989422804014327

double phonoc_bose_einstein(const double x, const double t) {
    return 1.0 / (exp(THZTOEVPARKB * x / t) - 1);
}

double phonoc_gaussian(const double x, const double sigma) {
    return INVSQRT2PI / sigma * exp(-x * x / 2 / sigma / sigma);
}

double phonoc_inv_sinh_occupation(const double x, const double t) {
    return 1.0 / sinh(x * THZTOEVPARKB / 2 / t);
}
