# naginterfaces.library.blas.dtrsm¶

naginterfaces.library.blas.dtrsm(side, uplo, transa, diag, m, alpha, a, b)[source]

dtrsm performs one of the matrix-matrix operations

where is a real triangular matrix, is an real matrix, and is a real scalar. denotes or equivalently .

No test for singularity or near-singularity of is included in this function. Such tests must be performed before calling this function.

For full information please refer to the NAG Library document for f06yj

https://support.nag.com/numeric/nl/nagdoc_30.1/flhtml/f06/f06yjf.html

Parameters
sidestr, length 1

Specifies whether is operated on from the left or the right.

is pre-multiplied from the left.

is post-multiplied from the right.

uplostr, length 1

Specifies whether is upper or lower triangular.

is upper triangular.

is lower triangular.

transastr, length 1

Specifies whether the operation involves or .

The operation involves .

or

The operation involves .

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.

mint

, the number of rows of the matrix ; the order of if .

alphafloat

The scalar .

afloat, array-like, shape

Note: the required extent for this argument in dimension 1 is determined as follows: if : ; if : ; otherwise: .

Note: the required extent for this argument in dimension 2 is determined as follows: if : ; if : ; otherwise: .

The triangular matrix ; is if , or if .

bfloat, array-like, shape

The matrix .

If , need not be set.

Returns
bfloat, ndarray, shape

The updated 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: 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.