$Id: check_for_nan.omh 3214 2014-03-18 20:50:38Z bradbell $
/* --------------------------------------------------------------------------
CppAD: C++ Algorithmic Differentiation: Copyright (C) 2003-14 Bradley M. Bell

CppAD is distributed under multiple licenses. This distribution is under
the terms of the 
                    Eclipse Public License Version 1.0.

A copy of this license is included in the COPYING file of this distribution.
Please visit http://www.coin-or.org/CppAD/ for information on other licenses.
-------------------------------------------------------------------------- */

$begin check_for_nan$$
$spell
	Cpp
	const
	bool
$$
$section Check an ADFun Object For Nan$$
$index nan, check ADFun$$
$index check, nan in ADFun$$
$index ADFun, check nan$$.

$head Syntax$$
$codei%f%.check_for_nan(%b%)
%$$
$icode%b% = %f%.check_for_nan()
%$$

$head Purpose$$
If $code NDEBUG$$ is not defined and
the result of a $cref/forward/forward_order/$$ or $cref/reverse/reverse_any/$$
calculation contains a  $cref nan$$,
CppAD halts with an error message.
This can be suppressed using $code check_for_nan$$.

$head f$$
For the syntax where $icode b$$ is an argument, 
$icode f$$ has prototype
$codei%
	ADFun<%Base%> %f%
%$$
(see $codei%ADFun<%Base%>%$$ $cref/constructor/FunConstruct/$$).
For the syntax where $icode b$$ is the result, 
$icode f$$ has prototype
$codei%
	const ADFun<%Base%> %f%
%$$

$head b$$
This argument or result has prototype
$codei%
	bool %b%
%$$
Future calls to $icode%f%.Forward%$$ will (will not) check for $code nan$$.
depending on if $icode b$$ is true (false).

$head Default$$
The value for this setting after construction of $icode f$$) is true.
The value of this setting is not affected by calling 
$cref Dependent$$ for this function object.

$head Example$$
$children%
	example/check_for_nan.cpp
%$$
The file
$cref check_for_nan.cpp$$ 
contains an example and test of these operations.
It returns true if it succeeds and false otherwise.

$end