\(\newcommand{\W}[1]{ \; #1 \; }\) \(\newcommand{\R}[1]{ {\rm #1} }\) \(\newcommand{\B}[1]{ {\bf #1} }\) \(\newcommand{\D}[2]{ \frac{\partial #1}{\partial #2} }\) \(\newcommand{\DD}[3]{ \frac{\partial^2 #1}{\partial #2 \partial #3} }\) \(\newcommand{\Dpow}[2]{ \frac{\partial^{#1}}{\partial {#2}^{#1}} }\) \(\newcommand{\dpow}[2]{ \frac{ {\rm d}^{#1}}{{\rm d}\, {#2}^{#1}} }\)
det_by_lu.hpp¶
View page sourceSource: det_by_lu¶
#
ifndef CPPAD_DET_BY_LU_HPP
#
define CPPAD_DET_BY_LU_HPP
# include <cppad/utility/vector.hpp>
# include <cppad/utility/lu_solve.hpp>
// BEGIN CppAD namespace
namespace CppAD {
template <class Scalar>
class det_by_lu {
private:
const size_t m_;
const size_t n_;
CppAD::vector<Scalar> A_;
CppAD::vector<Scalar> B_;
CppAD::vector<Scalar> X_;
public:
det_by_lu(size_t n) : m_(0), n_(n), A_(n * n)
{ }
template <class Vector>
Scalar operator()(const Vector &x)
{
Scalar logdet;
Scalar det;
int signdet;
size_t i;
// copy matrix so it is not overwritten
for(i = 0; i < 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 < n_ * n_; i++)
A_[i] = 0;
# endif
return det;
}
};
} // END CppAD namespace
# endif