naginterfaces.library.blas.dspr2

naginterfaces.library.blas.dspr2(uplo, alpha, x, y, ap)[source]

dspr2 computes the rank-2 update of a real symmetric matrix stored in packed form.

For full information please refer to the NAG Library document for f06ps

https://www.nag.com/numeric/nl/nagdoc_28.6/flhtml/f06/f06psf.html

Parameters
uplostr, length 1

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

The upper triangular part of is stored.

The lower triangular part of is stored.

alphafloat

The scalar .

xfloat, array-like, shape

The -element vector .

yfloat, array-like, shape

The -element vector .

apfloat, array-like, shape

The symmetric matrix , packed by columns.

Returns
apfloat, ndarray, shape

The updated matrix .

Raises
NagValueError
(errno )

On entry, error in parameter .

Constraint: or .

(errno )

On entry, error in parameter .

Constraint: .

(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.

dspr2 performs the symmetric rank-2 update operation

where is an real symmetric matrix, stored in packed form, and are -element real vectors, and is a real scalar.