man sorm2l (Fonctions bibliothèques) - 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',
NAME
SORM2L - 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 SORM2L(
- 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
SORM2L 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
as returned by SGEQLF. 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,K)
- The i-th column must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by SGEQLF in the last k columns 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. If SIDE = 'L', LDA >= max(1,M); if SIDE = 'R', LDA >= max(1,N).
- TAU (input) REAL array, dimension (K)
- TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by SGEQLF.
- 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 illegal value