sormr2(3)

NAME

SORMR2 - overwrite the general real m by n matrix C with

Q * C if SIDE = 'L' and TRANS = 'N', or Q'* C if SIDE = 'L' and

TRANS = 'T', or C * Q if SIDE = 'R' and TRANS = 'N', or C * Q'

if SIDE = 'R' and TRANS = 'T',

SYNOPSIS

SUBROUTINE  SORMR2(  SIDE, TRANS, M, N, K, A, LDA, TAU, C,
LDC, WORK, INFO )
    CHARACTER      SIDE, TRANS
    INTEGER        INFO, K, LDA, LDC, M, N
    REAL           A( LDA, * ), C( LDC, *  ),  TAU(  *  ),
WORK( * )

PURPOSE

SORMR2 overwrites the general real m by n matrix C with Q

* C if SIDE = 'L' and TRANS = 'N', or Q'* C if SIDE = 'L' and

TRANS = 'T', or C * Q if SIDE = 'R' and TRANS = 'N', or C * Q' if

SIDE = 'R' and TRANS = 'T', where Q is a real orthogonal matrix

defined as the product of k elementary reflectors

Q = H(1) H(2) . . . H(k)

as returned by SGERQF. Q is of order m if SIDE = 'L' and

of order n if SIDE = 'R'.

ARGUMENTS

SIDE (input) CHARACTER*1

= 'L': apply Q or Q' from the Left
= 'R': apply Q or Q' from the Right

TRANS (input) CHARACTER*1

= 'N': apply Q (No transpose)
= 'T': apply Q' (Transpose)

M (input) INTEGER

The number of rows of the matrix C. M >= 0.

N (input) INTEGER

The number of columns of the matrix C. N >= 0.

K (input) INTEGER

The number of elementary reflectors whose product

defines the matrix Q. If SIDE = 'L', M >= K >= 0; if SIDE = 'R',

N >= K >= 0.

A (input) REAL array, dimension

(LDA,M) if SIDE = 'L', (LDA,N) if SIDE = 'R' The

i-th row must contain the vector which defines the elementary re

flector H(i), for i = 1,2,...,k, as returned by SGERQF in the

last k rows of its array argument A. A is modified by the rou

tine but restored on exit.

LDA (input) INTEGER

The leading dimension of the array A. LDA >=

max(1,K).

TAU (input) REAL array, dimension (K)

TAU(i) must contain the scalar factor of the ele

mentary reflector H(i), as returned by SGERQF.

C (input/output) REAL array, dimension (LDC,N)

On entry, the m by n matrix C. On exit, C is

overwritten by Q*C or Q'*C or C*Q' or C*Q.

LDC (input) INTEGER

The leading dimension of the array C. LDC >=

max(1,M).

WORK (workspace) REAL array, dimension

(N) if SIDE = 'L', (M) if SIDE = 'R'

INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = -i, the i-th argument had an ille

gal value

LAPACK version 3.0 15 June 2000

SORMR2(3)