subroutine dorm22 (SIDE, TRANS, M, N, N1, N2, Q, LDQ, C, LDC, WORK, LWORK, INFO)
DORM22 multiplies a general matrix by a banded orthogonal matrix.
DORM22 multiplies a general matrix by a banded orthogonal matrix.
Purpose
DORM22 overwrites the general real M-by-N matrix C with SIDE = 'L' SIDE = 'R' TRANS = 'N': Q * C C * Q 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'. The orthogonal matrix Q processes a 2-by-2 block structure [ Q11 Q12 ] Q = [ ] [ Q21 Q22 ], where Q12 is an N1-by-N1 lower triangular matrix and Q21 is an N2-by-N2 upper triangular matrix.
Parameters:
SIDE is CHARACTER*1 = 'L': apply Q or Q**T from the Left; = 'R': apply Q or Q**T from the Right.
TRANS
TRANS is CHARACTER*1 = 'N': apply Q (No transpose); = 'C': apply Q**T (Conjugate transpose).
M
M is INTEGER The number of rows of the matrix C. M >= 0.
N
N is INTEGER The number of columns of the matrix C. N >= 0.
N1
N2
N1 is INTEGER N2 is INTEGER The dimension of Q12 and Q21, respectively. N1, N2 >= 0. The following requirement must be satisfied: N1 + N2 = M if SIDE = 'L' and N1 + N2 = N if SIDE = 'R'.
Q
Q is DOUBLE PRECISION array, dimension (LDQ,M) if SIDE = 'L' (LDQ,N) if SIDE = 'R'
LDQ
LDQ is INTEGER The leading dimension of the array Q. LDQ >= max(1,M) if SIDE = 'L'; LDQ >= max(1,N) if SIDE = 'R'.
C
C is DOUBLE PRECISION 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
LDC is INTEGER The leading dimension of the array C. LDC >= max(1,M).
WORK
WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)) On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
LWORK
LWORK is 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 >= M*N. If LWORK = -1, then a workspace query is assumed; the routine only calculates the optimal size of the WORK array, returns this value as the first entry of the WORK array, and no error message related to LWORK is issued by XERBLA.
INFO
INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value
Author:
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
Definition at line 165 of file dorm22.f.
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