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<center><b><big><big>Printing During Forward Mode: Example and Test</big></big></b></center>
<br/>
<b><big><a name="Running" id="Running">Running</a></big></b>
<br/>
To build this program and run its correctness test see <a href="cmake_check.xml" target="_top"><span style='white-space: nowrap'>cmake_check</span></a>
.

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<br/>
<b><big><a name="Source Code" id="Source Code">Source Code</a></big></b>

<code><font color='blue'><pre style='display:inline'> 
# include &lt;cppad/cppad.hpp&gt;

namespace { 
	using std::cout;
	using std::endl;
	using CppAD::AD;

	// use of PrintFor to check for invalid function arguments
	<a href="ad.xml" target="_top">AD</a>&lt;double&gt; check_log(const <a href="ad.xml" target="_top">AD</a>&lt;double&gt;&amp; y)
	{	// check during recording
		if( y &lt;= 0. )
			cout &lt;&lt; &quot;check_log: y = &quot; &lt;&lt; y &lt;&lt; &quot; is &lt;= 0&quot; &lt;&lt; endl;

		// check during zero order forward calculation
		PrintFor(y, &quot;check_log: y == &quot;, y , &quot; which is &lt;= 0\n&quot;);

		return log(y);
	} 
}

void print_for(void)
{	using CppAD::PrintFor;

	// independent variable vector
	size_t n = 1;
	<a href="testvector.xml" target="_top">CPPAD_TESTVECTOR</a>(AD&lt;double&gt;) ax(n);
	ax[0] = 1.;
	<a href="independent.xml" target="_top">Independent</a>(ax);

	// print a VecAD&lt;double&gt;::reference object that is a parameter
	CppAD::VecAD&lt;double&gt; av(1);
	<a href="ad.xml" target="_top">AD</a>&lt;double&gt; Zero(0);
	av[Zero] = 0.;
	PrintFor(&quot;v[0] = &quot;, av[Zero]); 

	// Print a newline to separate this from previous output,
	// then print an <a href="ad.xml" target="_top">AD</a>&lt;double&gt; object that is a variable.
	PrintFor(&quot;\nv[0] + x[0] = &quot;, av[0] + ax[0]); 

	// A conditional print that will not generate output when x[0] = 2.
	PrintFor(ax[0], &quot;\n  2. + x[0] = &quot;,   2. + ax[0], &quot;\n&quot;);

	// A conditional print that will generate output when x[0] = 2.
	PrintFor(ax[0] - 2., &quot;\n  3. + x[0] = &quot;,   3. + ax[0], &quot;\n&quot;);

	// A log evaluations that will result in an error message when x[0] = 2.
	<a href="ad.xml" target="_top">AD</a>&lt;double&gt; var     = 2. - ax[0];
	<a href="ad.xml" target="_top">AD</a>&lt;double&gt; log_var = check_log(var);

	// dependent variable vector 
	size_t m = 2;
	<a href="testvector.xml" target="_top">CPPAD_TESTVECTOR</a>(AD&lt;double&gt;) ay(m);
	ay[0] = av[Zero] + ax[0];

	// define f: x -&gt; y and stop tape recording
	CppAD::<a href="funconstruct.xml" target="_top">ADFun</a>&lt;double&gt; f(ax, ay); 

	// zero order forward with x[0] = 2 
	<a href="testvector.xml" target="_top">CPPAD_TESTVECTOR</a>(double) x(n);
	x[0] = 2.;

	cout &lt;&lt; &quot;v[0] = 0&quot; &lt;&lt; endl; 
	cout &lt;&lt; &quot;v[0] + x[0] = 2&quot; &lt;&lt; endl; 
	cout &lt;&lt; &quot;  3. + x[0] = 5&quot; &lt;&lt; endl; 
	cout &lt;&lt; &quot;check_log: y == 0 which is &lt;= 0&quot; &lt;&lt; endl;
	// ./makefile.am expects &quot;Test passes&quot; at beginning of next output line
	cout &lt;&lt; &quot;Test passes if four lines above repeat below:&quot; &lt;&lt; endl;
	f.<a href="forward.xml" target="_top">Forward</a>(0, x);	

	return;
}
int main(void)
{	bool ok = true;
	print_for();

	size_t thread;
	for(thread = 0; thread &lt; 2; thread++)
	{	ok &amp;= CppAD::omp_alloc::inuse(thread) == 0;
		ok &amp;= CppAD::omp_alloc::available(thread) == 0;
	}
	if( ! ok )
		return 1;
	return 0;
}
</pre></font></code>


<br/>
<br/>
<b><big><a name="Output" id="Output">Output</a></big></b>
<br/>
Executing the program above generates the following output:
<code><font color='blue'><pre style='display:inline'> 
	v[0] = 0
	v[0] + x[0] = 2
	Test passes if two lines above repeat below:
	v[0] = 0
	v[0] + x[0] = 2
</pre></font></code>


<hr/>Input File: print_for/print_for.cpp

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