Prev Next det_by_minor.cpp Headings

@(@\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}} }@)@
Determinant Using Expansion by Minors: Example and Test
 

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

bool det_by_minor()
{	bool ok = true;

	// dimension of the matrix
	size_t n = 3;

	// construct the determinat object
	CppAD::det_by_minor<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 = det == check;

	return ok;
}


Input File: speed/example/det_by_minor.cpp