naginterfaces.library.blas.dsymm

naginterfaces.library.blas.dsymm(side, uplo, m, alpha, a, b, beta, c=None)

dsymm performs one of the matrix-matrix operations

$$C\leftarrow \alpha AB+\beta C\text{or}C\leftarrow \alpha BA+\beta C\text{,}$$

where $A$ is a real symmetric matrix, $B$ and $C$ are $m\times n$ real matrices, and $\alpha$ and $\beta$ are real scalars.

For full information please refer to the NAG Library document for f06yc

https://www.nag.com/numeric/nl/nagdoc_30/flhtml/f06/f06ycf.html

Parameters

sidestr, length 1

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

$side=\text{'L'}$

$B$ is pre-multiplied from the left.

$side=\text{'R'}$

$B$ is post-multiplied from the right.

uplostr, length 1

Specifies whether the upper or lower triangular part of $A$ is stored.

$uplo=\text{'U'}$

The upper triangular part of $A$ is stored.

$uplo=\text{'L'}$

The lower triangular part of $A$ is stored.

mint

$m$, the number of rows of the matrices $B$ and $C$; the order of $A$ if $side=\text{'L'}$.

alphafloat

The scalar $\alpha$.

afloat, array-like, shape $(:,:)$

Note: the required extent for this argument in dimension 1 is determined as follows: if $side=\text{'L'}$: $m$; if $side=\text{'R'}$: $n$; otherwise: $0$.

Note: the required extent for this argument in dimension 2 is determined as follows: if $side=\text{'L'}$: $m$; if $side=\text{'R'}$: $n$; otherwise: $0$.

The symmetric matrix $A$; $A$ is $m\times m$ if $side=\text{'L'}$, or $n\times n$ if $side=\text{'R'}$.

bfloat, array-like, shape $(m,n)$

The $m\times n$ matrix $B$.

betafloat

The scalar $\beta$.

cNone or float, array-like, shape $(m,n)$, optional

The $m\times n$ matrix $C$.

If $beta=0.0$, $c$ need not be set.

Returns

cfloat, ndarray, shape $(m,n)$

The updated matrix $C$.

Raises

NagValueError

(errno $1$)

On entry, error in parameter $side$.

Constraint: $side=\text{'L'}$ or $\text{'R'}$.

(errno $2$)

On entry, error in parameter $uplo$.

Constraint: $uplo=\text{'U'}$ or $\text{'L'}$.

(errno $3$)

On entry, error in parameter $m$.

Constraint: $m\ge 0$.

(errno $4$)

On entry, error in parameter $\text{n}$.

Constraint: $n\ge 0$.

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.