dlasr (l) - Linux Man Pages
dlasr: applies a sequence of plane rotations to a real matrix A,
NAMEDLASR - applies a sequence of plane rotations to a real matrix A,
- SUBROUTINE DLASR(
- SIDE, PIVOT, DIRECT, M, N, C, S, A, LDA )
- CHARACTER DIRECT, PIVOT, SIDE
- INTEGER LDA, M, N
- DOUBLE PRECISION A( LDA, * ), C( * ), S( * )
PURPOSEDLASR applies a sequence of plane rotations to a real matrix A, from either the left or the right.
When SIDE = aqLaq, the transformation takes the form
and when SIDE = aqRaq, the transformation takes the form
where P is an orthogonal matrix consisting of a sequence of z plane rotations, with z = M when SIDE = aqLaq and z = N when SIDE = aqRaq, and P**T is the transpose of P.
When DIRECT = aqFaq (Forward sequence), then
and when DIRECT = aqBaq (Backward sequence), then
where P(k) is a plane rotation matrix defined by the 2-by-2 rotation
When PIVOT = aqVaq (Variable pivot), the rotation is performed for the plane (k,k+1), i.e., P(k) has the form