Determinant Using Lu Factorization: Example and Test
Keywords: determinant using lu factorization: example test minors

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Determinant Using Lu Factorization: Example and Test
`

    # include <cppad/cppad.hpp>
    # include <cppad/speed/det_by_lu.hpp>

    bool det_by_lu()
    {	bool ok = true;

    	// dimension of the matrix
    	size_t n = 3;

    	// construct the determinat object
    	CppAD::det_by_lu<double> Det(n);

    	double  a[] = {
    		1., 2., 3.,  // a[0] a[1] a[2]
    		3., 2., 1.,  // a[3] a[4] a[5]
    		2., 1., 2.   // a[6] a[7] a[8]
    	};
    	CPPAD_TESTVECTOR(double) A(9);
    	size_t i;
    	for(i = 0; i < 9; i++)
    		A[i] = a[i];

    	// evaluate the determinant
    	double det = Det(A);

    	double check;
    	check = a[0]*(a[4]*a[8] - a[5]*a[7])
    	      - a[1]*(a[3]*a[8] - a[5]*a[6])
    	      + a[2]*(a[3]*a[7] - a[4]*a[6]);

    	ok = CppAD::NearEqual(det, check, 1e-10, 1e-10);

    	return ok;
    }

`

Input File: speed/example/det_by_lu.cpp