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<center><b><big><big>Source: det_by_lu</big></big></b></center>
<code><font color="blue"># ifndef CPPAD_DET_BY_LU_INCLUDED 
<code><span style='white-space: nowrap'><br/>
</span></code># define CPPAD_DET_BY_LU_INCLUDED

<pre style='display:inline'> 
# include &lt;cppad/cppad.hpp&gt;
# include &lt;complex&gt;

// BEGIN CppAD namespace
namespace CppAD {

// The AD complex case is used by examples by not used by speed tests 
// Must define a specializatgion of LeqZero,AbsGeq for the ADComplex case
typedef std::complex&lt;double&gt;     Complex;
typedef CppAD::<a href="ad.xml" target="_top">AD</a>&lt;Complex&gt;     ADComplex;
CPPAD_BOOL_UNARY(Complex,  LeqZero )
CPPAD_BOOL_BINARY(Complex, AbsGeq )

template &lt;class Scalar&gt;
class det_by_lu {
private:
	const size_t m_;
	const size_t n_;
	<a href="testvector.xml" target="_top">CPPAD_TESTVECTOR</a>(Scalar) A_;
	<a href="testvector.xml" target="_top">CPPAD_TESTVECTOR</a>(Scalar) B_;
	<a href="testvector.xml" target="_top">CPPAD_TESTVECTOR</a>(Scalar) X_;
public:
	det_by_lu(size_t n) : m_(0), n_(n), A_(n * n)
	{	}

	template &lt;class Vector&gt;
	inline Scalar operator()(const Vector &amp;x)
	{
		using CppAD::exp;

		Scalar       logdet;
		Scalar       det;
		int          signdet;
		size_t       i;

		// copy matrix so it is not overwritten
		for(i = 0; i &lt; n_ * n_; i++)
			A_[i] = x[i];
 
		// comput log determinant
		signdet = CppAD::LuSolve(
			n_, m_, A_, B_, X_, logdet);

/*
		// Do not do this for speed test because it makes floating 
		// point operation sequence very simple.
		if( signdet == 0 )
			det = 0;
		else	det =  Scalar( signdet ) * exp( logdet );
*/

		// convert to determinant
		det     = Scalar( signdet ) * exp( logdet ); 

# ifdef FADBAD
		// Fadbad requires tempories to be set to constants
		for(i = 0; i &lt; n_ * n_; i++)
			A_[i] = 0;
# endif

		return det;
	}
};
} // END CppAD namespace
</pre>


# endif
</font></code>


<hr/>Input File: omh/det_by_lu_hpp.omh

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