SORMHR(3F)SORMHR(3F)NAME
SORMHR - overwrite the general real M-by-N matrix C with SIDE = 'L'
SIDE = 'R' TRANS = 'N'
SYNOPSIS
SUBROUTINE SORMHR( SIDE, TRANS, M, N, ILO, IHI, A, LDA, TAU, C, LDC,
WORK, LWORK, INFO )
CHARACTER SIDE, TRANS
INTEGER IHI, ILO, INFO, LDA, LDC, LWORK, M, N
REAL A( LDA, * ), C( LDC, * ), TAU( * ), WORK( LWORK )
PURPOSE
SORMHR overwrites the general real M-by-N matrix C with TRANS = 'T':
Q**T * C C * Q**T
where Q is a real orthogonal matrix of order nq, with nq = m if SIDE =
'L' and nq = n if SIDE = 'R'. Q is defined as the product of IHI-ILO
elementary reflectors, as returned by SGEHRD:
Q = H(ilo) H(ilo+1) . . . H(ihi-1).
ARGUMENTS
SIDE (input) CHARACTER*1
= 'L': apply Q or Q**T from the Left;
= 'R': apply Q or Q**T from the Right.
TRANS (input) CHARACTER*1
= 'N': No transpose, apply Q;
= 'T': Transpose, apply Q**T.
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.
ILO (input) INTEGER
IHI (input) INTEGER ILO and IHI must have the same values as
in the previous call of SGEHRD. Q is equal to the unit matrix
except in the submatrix Q(ilo+1:ihi,ilo+1:ihi). If SIDE = 'L',
then 1 <= ILO <= IHI <= M, if M > 0, and ILO = 1 and IHI = 0, if
M = 0; if SIDE = 'R', then 1 <= ILO <= IHI <= N, if N > 0, and
ILO = 1 and IHI = 0, if N = 0.
A (input) REAL array, dimension
(LDA,M) if SIDE = 'L' (LDA,N) if SIDE = 'R' The vectors which
define the elementary reflectors, as returned by SGEHRD.
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SORMHR(3F)SORMHR(3F)
LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(1,M) if SIDE =
'L'; LDA >= max(1,N) if SIDE = 'R'.
TAU (input) REAL array, dimension
(M-1) if SIDE = 'L' (N-1) if SIDE = 'R' TAU(i) must contain the
scalar factor of the elementary reflector H(i), as returned by
SGEHRD.
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**T*C or C*Q**T or C*Q.
LDC (input) INTEGER
The leading dimension of the array C. LDC >= max(1,M).
WORK (workspace/output) REAL array, dimension (LWORK)
On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
LWORK (input) INTEGER
The dimension of the array WORK. If SIDE = 'L', LWORK >=
max(1,N); if SIDE = 'R', LWORK >= max(1,M). For optimum
performance LWORK >= N*NB if SIDE = 'L', and LWORK >= M*NB if
SIDE = 'R', where NB is the optimal blocksize.
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
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