inline T slowDet(const ConstMatrixBase<T, BaseClass>& l)
{
if (!l.isSquare() || (l.rows() <= 1))
{
MatrixException e("Invalid matrix for det()");
GPSTK_THROW(e);
}
// go recursion!
if (l.rows() == 2)
return l(0,0)*l(1,1) - l(0,1)*l(1,0);
else
{
// use v[0,0] * det(minor matrix(0,0)) +
// v[0,1] * det(minor matrix(0,1)) + ...
size_t i;
int sign;
T det = 0;
for (i = 0; i < l.rows(); i++)
{
sign = (i % 2) ? -1 : 1;
if (l(0,i) != 0)
det += sign * l(0,i) * slowDet(minorMatrix(l,0,i));
}
return det;
}
}
double matrixDeterminant(double **A, int n){
int i;
double det=0;
double **B;
B=allocateDoubleMatrix(n-1, n-1);
if(n==2){
det=(A[0][0]*A[1][1])-(A[0][1]*A[1][0]);
}
else{
for(i=0;i<n;i++){
B=minorMatrix(A, n, i, 0);
det += pow(-1,i)*A[0][i]*matrixDeterminant(B,n-1);
}
}
return(det);
}
