/* mpfr_sech - Hyperbolic secant function = 1/cosh.

Copyright 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
Contributed by the Arenaire and Cacao projects, INRIA.

This file is part of the GNU MPFR Library.

The GNU MPFR Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version.

The GNU MPFR Library 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 Lesser General Public
License for more details.

You should have received a copy of the GNU Lesser General Public License
along with the GNU MPFR Library; see the file COPYING.LIB.  If not, write to
the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
MA 02110-1301, USA. */

/* The hyperbolic secant function is defined by sech(x)=1/cosh(x):
    csc (NaN) = NaN.
    csc (+Inf) = csc (-Inf) = 0+.
    csc (+0) = csc (-0) = 1.
 */

#define FUNCTION mpfr_sech
#define INVERSE  mpfr_cosh
#define ACTION_NAN(y) do { MPFR_SET_NAN(y); MPFR_RET_NAN; } while (1)
#define ACTION_INF(y) return mpfr_set_ui (y, 0, GMP_RNDN)
#define ACTION_ZERO(y,x) return mpfr_set_ui (y, 1, rnd_mode)
/* for x near 0, sech(x) = 1 - x^2/2 + ..., more precisely |sech(x)-1| <= x^2/2
   for |x| <= 1. The tiny action is the same as for cos(x). */
#define ACTION_TINY(y,x,r) \
  MPFR_FAST_COMPUTE_IF_SMALL_INPUT(y, __gmpfr_one, -2 * MPFR_GET_EXP (x), 1, \
                                   0, r, inexact = _inexact; goto end)

#include "gen_inverse.h"