nag_det_real_gen (f03bac) computes the determinant of a real
by
matrix
.
nag_dgetrf (f07adc) must be called first to supply the matrix
in factorized form.
nag_det_real_gen (f03bac) computes the determinant of a real
by
matrix
that has been factorized by a call to
nag_dgetrf (f07adc). The determinant of
is the product of the diagonal elements of
with the correct sign determined by the row interchanges.
The accuracy of the determinant depends on the conditioning of the original matrix. For a detailed error analysis, see page 107 of
Wilkinson and Reinsch (1971).
This example computes the
factorization with partial pivoting, and calculates the determinant, of the real matrix