RE: Matrix determinant

Hi, 
We didn't find a determinant implemented in MTL as well, therefore we implemented our own. It works fine for our needs and I include the code in the following:

#include <mtl/matrix.h>
#include <mtl/mtl.h>
#include <mtl/dense1D.h>
#include <mtl/utils.h>
#include <mtl/lu.h>

/*!This function calculates the determinant of a matrix */
template<class MatrixType>
double lu_det(const MatrixType& _Matrix){

	int size = _Matrix.nrows();
	MatrixType LU(size,size);
	dense1D<int> pvector(size);

	copy(_Matrix, LU);
	lu_factor(LU, pvector);

	//For every permutation of rows the product of 
	//diagonal elements has to be multyplied by -1
	int sign = 1;
	for (int i = 0 ; i < size ; ++i){
   		if ( pvector[i] != i+1 ) 
       		sign *= -1; 
	}

	typename MatrixType::iterator iter;
	iter = LU.begin();

	double det = 1.0;
	unsigned ind = 0;
	for ( iter = LU.begin(); iter != LU.end(); ++iter ){
		ind = iter.index(); 
   		det *= LU(ind, ind);
	}

	det *= sign;
	return det;
}

Kind regards
ok


---------------------------------------------------- 
Oliver Koenig 
Center of Structure Technologies 
Institute of Mechanical Systems 
LEO C12 
ETH Zurich 
CH-8092 Zurich 
Phone : +41 1 632 23 28 
Fax :   +41 1 632 17 02 
Mail :  [email protected] 
WWW :  http://www.imes.ethz.ch/st/ 
---------------------------------------------------- 

-----Original Message----- 
From: Enes Makalic [mailto:[email protected]] 
Sent: Freitag, 30. August 2002 08:49 
To: [email protected] 
Subject: MTL: Matrix determinant 
Hi, 
I am trying to calculate the determinant of a matrix in MTL 
and cant seem to find any functions to do this. 
Is this possible in MTL, if so, how ? 
Thank you, 
- Enes. 

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