naginterfaces.library.blas.zspmv

naginterfaces.library.blas.zspmv(uplo, alpha, ap, x, beta, y)

zspmv performs the matrix-vector operation

$$y\leftarrow \alpha Ax+\beta y$$

where $A$ is an $n\times n$ complex symmetric matrix stored in packed form, $x$ and $y$ are $n$-element complex vectors, and $\alpha$ and $\beta$ are complex scalars.

For full information please refer to the NAG Library document for f06tc

https://support.nag.com/numeric/nl/nagdoc_30.3/flhtml/f06/f06tcf.html

Parameters

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.

alphacomplex

The scalar $\alpha$.

apcomplex, array-like, shape $(n\times (n+1)/2)$

The $n\times n$ symmetric matrix $A$, packed by columns.

xcomplex, array-like, shape $\left(n\right)$

The $n$-element vector $x$.

betacomplex

The scalar $\beta$.

ycomplex, array-like, shape $\left(n\right)$

The $n$-element vector $y$.

Returns

ycomplex, ndarray, shape $\left(n\right)$

The updated vector $y$.

Raises

NagValueError

(errno $1$)

On entry, error in parameter $uplo$.

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

(errno $2$)

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

Constraint: $n\ge 0$.

(errno $6$)

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

Constraint: $\text{incx}\ne 0$.

(errno $9$)

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

Constraint: $\text{incy}\ne 0$.

Notes

No equivalent traditional C interface for this routine exists in the NAG Library.