# naginterfaces.library.blas.dutsqr¶

naginterfaces.library.blas.dutsqr(side, k1, k2, c, s, a)[source]

dutsqr performs a or factorization of the product of a real upper triangular matrix and a real matrix of plane rotations.

For full information please refer to the NAG Library document for f06qt

https://www.nag.com/numeric/nl/nagdoc_29.2/flhtml/f06/f06qtf.html

Parameters
sidestr, length 1

Specifies whether is applied from the left or the right in the transformation.

is applied from the left.

is applied from the right.

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 upper triangular matrix .

Returns
cfloat, ndarray, shape

holds the cosine of the rotation , for .

sfloat, ndarray, shape

holds the sine of the rotation , for .

afloat, ndarray, shape

The upper triangular matrix .

Raises
NagValueError
(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.

dutsqr performs one of the transformations

where is a given real upper triangular matrix, is a given real orthogonal matrix, and is a real orthogonal matrix chosen to make upper triangular. Both and are represented as sequences of plane rotations in planes to .

If ,

where and .

If ,

where and .

In either case and are rotations in the plane.

The rotation part of or has the form