# naginterfaces.library.blas.dsysrc¶

naginterfaces.library.blas.dsysrc(uplo, pivot, direct, k1, k2, c, s, a)[source]

dsysrc performs an orthogonal similarity transformation (as a sequence of plane rotations) of a real symmetric matrix.

For full information please refer to the NAG Library document for f06qm

https://www.nag.com/numeric/nl/nagdoc_28.7/flhtml/f06/f06qmf.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.

pivotstr, length 1

Specifies the plane rotated by .

(variable pivot)

rotates the plane.

(top pivot)

rotates the plane.

(bottom pivot)

rotates the plane.

directstr, length 1

Specifies the sequence direction.

(forward sequence)

.

(backward sequence)

.

k1int

The value .

k2int

The value .

cfloat, array-like, shape

must hold , the cosine of the rotation , for .

sfloat, array-like, shape

must hold , the sine of the rotation , for .

afloat, array-like, shape

The symmetric matrix .

Returns
afloat, ndarray, shape

The transformed 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: .

Notes

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

dsysrc performs the transformation

where is an real symmetric matrix, and is a real orthogonal matrix defined as a sequence of plane rotations, , applied in planes to .

The plane rotation part of is assumed to have the form