naginterfaces.library.lapacklin.dgetri

naginterfaces.library.lapacklin.dgetri(a, ipiv)[source]

dgetri computes the inverse of a real matrix , where has been factorized by dgetrf().

For full information please refer to the NAG Library document for f07aj

https://www.nag.com/numeric/nl/nagdoc_27.3/flhtml/f07/f07ajf.html

Parameters
afloat, array-like, shape

The factorization of , as returned by dgetrf().

ipivint, array-like, shape

The pivot indices, as returned by dgetrf().

Returns
afloat, ndarray, shape

The factorization is overwritten by the matrix .

Raises
NagValueError
(errno )

On entry, error in parameter .

Constraint: .

Warns
NagAlgorithmicWarning
(errno )

Element of the diagonal is zero. is singular, and the inverse of cannot be computed.

Notes

dgetri is used to compute the inverse of a real matrix , the function must be preceded by a call to dgetrf(), which computes the factorization of as . The inverse of is computed by forming and then solving the equation for .

References

Du Croz, J J and Higham, N J, 1992, Stability of methods for matrix inversion, IMA J. Numer. Anal. (12), 1–19