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<?xml version='1.0'?>
<html xmlns='http://www.w3.org/1999/xhtml'
      xmlns:math='http://www.w3.org/1998/Math/MathML'
>
<head>
<title>ADFun Operation Sequence Optimization: Example and Test</title>
<meta http-equiv='Content-Type' content='text/html' charset='utf-8'/>
<meta name="description" id="description" content="ADFun Operation Sequence Optimization: Example and Test"/>
<meta name="keywords" id="keywords" content=" adfun operation sequence optimization: example and test optimize "/>
<style type='text/css'>
body { color : black }
body { background-color : white }
A:link { color : blue }
A:visited { color : purple }
A:active { color : purple }
</style>
<script type='text/javascript' language='JavaScript' src='_optimize.cpp_xml.js'>
</script>
</head>
<body>
<table><tr>
<td>
<a href="http://www.coin-or.org/CppAD/" target="_top"><img border="0" src="_image.gif"/></a>
</td>
<td><a href="optimize.xml" target="_top">Prev</a>
</td><td><a href="check_for_nan.xml" target="_top">Next</a>
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<option>external</option>
</select>
</td>
<td>
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<option>CppAD-&gt;</option>
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<option>Introduction</option>
<option>AD</option>
<option>ADFun</option>
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<option>library</option>
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<select onchange='choose_down2(this)'>
<option>ADFun-&gt;</option>
<option>Independent</option>
<option>FunConstruct</option>
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<option>seq_property</option>
<option>FunEval</option>
<option>Drivers</option>
<option>FunCheck</option>
<option>optimize</option>
<option>check_for_nan</option>
</select>
</td>
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<option>optimize-&gt;</option>
<option>optimize.cpp</option>
</select>
</td>
<td>optimize.cpp</td>
<td>Headings</td>
</tr></table><br/>


<center><b><big><big>ADFun Operation Sequence Optimization: Example and Test</big></big></b></center>
<code><font color="blue"><pre style='display:inline'> 
# include &lt;cppad/cppad.hpp&gt;
namespace {
	template &lt;class Float&gt;
	void fun(const Float&amp; x, Float&amp; y, size_t&amp; n_var, size_t&amp; n_opt)
	{	using CppAD::exp;

	 	// Create a variable that is optimized out because 
	 	// it is only used in the comparision operation.
		Float a = 1. / x;
		n_var += 1;
		n_opt += 0;

		// Create a variable that is used by the result
		Float b = x * 5.;
		n_var += 1;
		n_opt += 1;

		Float c;
		if( a &lt; x )  
			c = b / 3.; // only one variable created by this choice
		else	c = b / 2.;
		n_var += 1;
		n_opt += 1;

		// Create a variable that is optimized out because it
		// will always have the same value as b
		Float d = 5. * x;
		n_var += 1;
		n_opt += 0;

		// Create three variables that will be converted to one
		// cumulative summation. Note that a is not connected to 
		// the result y (in the operation sequence).
		y      = 1. + b + c + d; 
		n_var += 3;
		n_opt += 1;
	}
}

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

	// domain space vector
	size_t n  = 1;
	<a href="testvector.xml" target="_top">CPPAD_TESTVECTOR</a>(AD&lt;double&gt;) X(n);
	X[0]      = .5; 

	// declare independent variables and start tape recording
	CppAD::<a href="independent.xml" target="_top">Independent</a>(X);
	size_t n_var = 1 + n; // one phantom variable at the beginning
	size_t n_opt = 1 + n; // and one for each independent variable

	// range space vector 
	size_t m = 1;
	<a href="testvector.xml" target="_top">CPPAD_TESTVECTOR</a>(AD&lt;double&gt;) Y(m);
	fun(X[0], Y[0], n_var, n_opt);

	// create f: X -&gt; Y and stop tape recording
	CppAD::<a href="funconstruct.xml" target="_top">ADFun</a>&lt;double&gt; F(X, Y);
	ok &amp;= (F.size_var() == n_var);

	// Check zero order forward mode on the original operation sequence
	<a href="testvector.xml" target="_top">CPPAD_TESTVECTOR</a>(double) x(n), y(m);
	x[0] = Value(X[0]);
	size_t i = 0; // temporary variable (we do not use value)
	double check;
	fun(x[0], check, i, i);
	y   = F.<a href="forward.xml" target="_top">Forward</a>(0, x);
	ok &amp;= (y[0] == check);

	// Optimize the operation sequence
	F.optimize();
	ok &amp;= (F.size_var() == n_opt);

	// Check result for a zero order calculation.
	// This has already been checked if NDEBUG is not defined.
	fun(x[0], check, i, i);
	ok &amp;= (y[0] == check);
	y   = F.<a href="forward.xml" target="_top">Forward</a>(0, x);
	return ok;
}

</pre>

</font></code>


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

</body>
</html>