DORML2 - 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 DORML2( SIDE, TRANS, M, N, K, A, LDA, TAU, C,
LDC, WORK, INFO )
CHARACTER SIDE, TRANS
INTEGER INFO, K, LDA, LDC, M, N
DOUBLE PRECISION A( LDA, * ), C( LDC, * ),
TAU( * ), WORK( * )
PURPOSE
DORML2 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(k) . . . H(2) H(1)
as returned by DGELQF. 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) DOUBLE PRECISION array, dimension
(LDA,M) if SIDE = 'L', (LDA,N) if SIDE = 'R' The
i-th row must contain the vector which defines the
returned by DGELQF in the first k rows of its
array argument A. A is modified by the routine
but restored on exit.
LDA (input) INTEGER
The leading dimension of the array A. LDA >=
max(1,K).
TAU (input) DOUBLE PRECISION array, dimension (K)
TAU(i) must contain the scalar factor of the ele
mentary reflector H(i), as returned by DGELQF.
C (input/output) DOUBLE PRECISION 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) DOUBLE PRECISION 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
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