naginterfaces.library.lapacklin.dtptri

naginterfaces.library.lapacklin.dtptri(uplo, diag, n, ap)[source]

dtptri computes the inverse of a real triangular matrix, using packed storage.

For full information please refer to the NAG Library document for f07uj

https://www.nag.com/numeric/nl/nagdoc_27.3/flhtml/f07/f07ujf.html

Parameters
uplostr, length 1

Specifies whether is upper or lower triangular.

is upper triangular.

is lower triangular.

diagstr, length 1

Indicates whether is a nonunit or unit triangular matrix.

is a nonunit triangular matrix.

is a unit triangular matrix; the diagonal elements are not referenced and are assumed to be .

nint

, the order of the matrix .

apfloat, array-like, shape

The triangular matrix , packed by columns.

Returns
apfloat, ndarray, shape

is overwritten by , using the same storage format as described above.

Raises
NagValueError
(errno )

On entry, error in parameter .

Constraint: or .

(errno )

On entry, error in parameter .

Constraint: or .

(errno )

On entry, error in parameter .

Constraint: .

Warns
NagAlgorithmicWarning
(errno )

Element of the diagonal is exactly zero. is singular its inverse cannot be computed.

Notes

dtptri forms the inverse of a real triangular matrix , using packed storage. Note that the inverse of an upper (lower) triangular matrix is also upper (lower) triangular.

References

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