naginterfaces.library.blas.dtrmv

naginterfaces.library.blas.dtrmv(uplo, trans, diag, a, x)[source]

dtrmv computes the matrix-vector product for a real triangular matrix or its transpose.

For full information please refer to the NAG Library document for f06pf

https://www.nag.com/numeric/nl/nagdoc_28.7/flhtml/f06/f06pff.html

Parameters
uplostr, length 1

Specifies whether is upper or lower triangular.

is upper triangular.

is lower triangular.

transstr, length 1

Specifies the operation to be performed.

.

or

.

diagstr, length 1

Specifies whether has nonunit or unit diagonal elements.

The diagonal elements are stored explicitly.

The diagonal elements are assumed to be , and are not referenced.

afloat, array-like, shape

The triangular matrix .

xfloat, array-like, shape

The -element vector .

Returns
xfloat, ndarray, shape

The updated vector .

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: .

Notes

In the NAG Library the traditional C interface for this routine uses a different algorithmic base. Please contact NAG if you have any questions about compatibility.

dtrmv performs one of the matrix-vector operations

where is an real triangular matrix, and is an -element real vector.