naginterfaces.library.lapacklin.dtrtrs

naginterfaces.library.lapacklin.dtrtrs(uplo, trans, diag, a, b)[source]

dtrtrs solves a real triangular system of linear equations with multiple right-hand sides, or .

For full information please refer to the NAG Library document for f07te

https://www.nag.com/numeric/nl/nagdoc_27.3/flhtml/f07/f07tef.html

Parameters
uplostr, length 1

Specifies whether is upper or lower triangular.

is upper triangular.

is lower triangular.

transstr, length 1

Indicates the form of the equations.

The equations are of the form .

or

The equations are of the form .

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 .

afloat, array-like, shape

The triangular matrix .

bfloat, array-like, shape

The right-hand side matrix .

Returns
bfloat, ndarray, shape

The solution matrix .

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: or .

(errno )

On entry, error in parameter .

Constraint: .

(errno )

On entry, error in parameter .

Constraint: .

Warns
NagAlgorithmicWarning
(errno )

Element of the diagonal is exactly zero. is singular and the solution has not been computed.

Notes

dtrtrs solves a real triangular system of linear equations or .

References

Golub, G H and Van Loan, C F, 1996, Matrix Computations, (3rd Edition), Johns Hopkins University Press, Baltimore

Higham, N J, 1989, The accuracy of solutions to triangular systems, SIAM J. Numer. Anal. (26), 1252–1265