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<center><b><big><big>ADFun Checking For Nan: Example and Test</big></big></b></center>
<code><font color="blue"><pre style='display:inline'> 
# include &lt;cppad/cppad.hpp&gt;

namespace {
	void myhandler(
		bool known       ,
		int  line        ,
		const char *file ,
		const char *exp  ,
		const char *msg  )
	{	// error handler must not return, so throw an exception
		throw std::string(&quot;myhandler&quot;);
	}
}

bool check_for_nan(void)
{	bool ok = true;
	using CppAD::AD;

	// replace the default CppAD error handler
	CppAD::ErrorHandler info(myhandler);

	<a href="testvector.xml" target="_top">CPPAD_TESTVECTOR</a>(AD&lt;double&gt;) ax(2), ay(2);
	ax[0] = 0.0;
	ax[1] = 1.0;
	CppAD::<a href="independent.xml" target="_top">Independent</a>(ax);
	ay    = ax;
	CppAD::<a href="funconstruct.xml" target="_top">ADFun</a>&lt;double&gt; f(ax, ay);

	<a href="testvector.xml" target="_top">CPPAD_TESTVECTOR</a>(double) x(2), y(2);
	x[0] = 2.0;
	x[1] = CppAD::nan(0.0);

	// use try / catch because this causes an exception
	// (assuming that NDEBUG is not defined)
	f.check_for_nan(true);
	try {
		y = f.<a href="forward.xml" target="_top">Forward</a>(0, x);

		// should never reach here
		ok = false;
	}
	catch(std::string msg)
	{	ok &amp;= msg == &quot;myhandler&quot;;
	} 

	// now do calculation without an exception
	f.check_for_nan(false);
	y = f.<a href="forward.xml" target="_top">Forward</a>(0, x);
	ok &amp;= y[0] == x[0];
	ok &amp;= CppAD::isnan( y[1] ); 
	
	return ok;
}

</pre>

</font></code>


<hr/>Input File: example/check_for_nan.cpp

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