naginterfaces.library.blas.dsyr2

naginterfaces.library.blas.dsyr2(uplo, alpha, x, y, a)[source]

dsyr2 computes the rank-2 update of a real symmetric matrix.

For full information please refer to the NAG Library document for f06pr

https://www.nag.com/numeric/nl/nagdoc_28.7/flhtml/f06/f06prf.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 .

afloat, array-like, shape

The symmetric matrix .

Returns
afloat, 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.

dsyr2 performs the symmetric rank-2 update operation

where is an real symmetric matrix, and are -element real vectors, and is a real scalar.