# ifndef CPPAD_CORE_EXPM1_HPP
# define CPPAD_CORE_EXPM1_HPP
/* --------------------------------------------------------------------------
CppAD: C++ Algorithmic Differentiation: Copyright (C) 2003-17 Bradley M. Bell

CppAD is distributed under the terms of the
             Eclipse Public License Version 2.0.

This Source Code may also be made available under the following
Secondary License when the conditions for such availability set forth
in the Eclipse Public License, Version 2.0 are satisfied:
      GNU General Public License, Version 2.0 or later.
---------------------------------------------------------------------------- */

/*
-------------------------------------------------------------------------------
$begin expm1$$
$spell
    exp
    expm1
    const
    Vec
    std
    cmath
    CppAD
$$
$section The Exponential Function Minus One: expm1$$

$head Syntax$$
$icode%y% = expm1(%x%)%$$

$head Description$$
Returns the value of the exponential function minus one which is defined
by $icode%y% == exp(%x%) - 1%$$.

$head x, y$$
See the $cref/possible types/unary_standard_math/Possible Types/$$
for a unary standard math function.

$head CPPAD_USE_CPLUSPLUS_2011$$

$subhead true$$
If this preprocessor symbol is true ($code 1$$),
and $icode x$$ is an AD type,
this is an $cref/atomic operation/glossary/Operation/Atomic/$$.

$subhead false$$
If this preprocessor symbol is false ($code 0$$),
CppAD uses the representation
$latex \[
\R{expm1} (x) = \exp(x) - 1
\] $$
to compute this function.

$head Example$$
$children%
    example/general/expm1.cpp
%$$
The file
$cref expm1.cpp$$
contains an example and test of this function.

$end
-------------------------------------------------------------------------------
*/
# include <cppad/configure.hpp>
# if ! CPPAD_USE_CPLUSPLUS_2011

// BEGIN CppAD namespace
namespace CppAD {

template <class Type>
Type expm1_template(const Type &x)
{   return CppAD::exp(x) - Type(1);
}

inline float expm1(const float &x)
{   return expm1_template(x); }

inline double expm1(const double &x)
{   return expm1_template(x); }

template <class Base>
AD<Base> expm1(const AD<Base> &x)
{   return expm1_template(x); }

template <class Base>
AD<Base> expm1(const VecAD_reference<Base> &x)
{   return expm1_template( x.ADBase() ); }


} // END CppAD namespace

# endif // CPPAD_USE_CPLUSPLUS_2011
# endif // CPPAD_EXPM1_INCLUDED
