/* specfunc/gsl_sf_lambert.h
 * 
 * Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001 Gerard Jungman
 * 
 * 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.
 */

/* Author:  G. Jungman */

#ifndef __GSL_SF_LAMBERT_H__
#define __GSL_SF_LAMBERT_H__

#include <gsl/gsl_sf_result.h>

#undef __BEGIN_DECLS
#undef __END_DECLS
#ifdef __cplusplus
# define __BEGIN_DECLS extern "C" {
# define __END_DECLS }
#else
# define __BEGIN_DECLS /* empty */
# define __END_DECLS /* empty */
#endif

__BEGIN_DECLS


/* Lambert's Function W_0(x)
 *
 * W_0(x) is the principal branch of the
 * implicit function defined by W e^W = x.
 *
 * -1/E < x < \infty
 *
 * exceptions: GSL_EMAXITER;
 */
int     gsl_sf_lambert_W0_e(double x, gsl_sf_result * result);
double  gsl_sf_lambert_W0(double x);


/* Lambert's Function W_{-1}(x)
 *
 * W_{-1}(x) is the second real branch of the
 * implicit function defined by W e^W = x.
 * It agrees with W_0(x) when x >= 0.
 *
 * -1/E < x < \infty
 *
 * exceptions: GSL_MAXITER;
 */
int     gsl_sf_lambert_Wm1_e(double x, gsl_sf_result * result);
double  gsl_sf_lambert_Wm1(double x);


__END_DECLS

#endif /* __GSL_SF_LAMBERT_H__ */
