# ifndef CPPAD_CORE_LOG1P_HPP
# define CPPAD_CORE_LOG1P_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 log1p$$
$spell
    CppAD
$$

$section The Logarithm of One Plus Argument: log1p$$

$head Syntax$$
$icode%y% = log1p(%x%)%$$

$head Description$$
Returns the value of the logarithm of one plus argument which is defined
by $icode%y% == log(1 + %x%)%$$.

$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 \[
\R{log1p} (x) = \log(1 + x)
\] $$
to compute this function.

$head Example$$
$children%
    example/general/log1p.cpp
%$$
The file
$cref log1p.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 log1p_template(const Type &x)
{   return CppAD::log(Type(1) + x);
}

inline float log1p(const float &x)
{   return log1p_template(x); }

inline double log1p(const double &x)
{   return log1p_template(x); }

template <class Base>
AD<Base> log1p(const AD<Base> &x)
{   return log1p_template(x); }

template <class Base>
AD<Base> log1p(const VecAD_reference<Base> &x)
{   return log1p_template( x.ADBase() ); }


} // END CppAD namespace

# endif // CPPAD_USE_CPLUSPLUS_2011
# endif // CPPAD_LOG1P_INCLUDED
