dorm22.f3
Usage
Functions/Subroutines
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.
Function/Subroutine Documentation
subroutine dorm22 (character side, character trans, integer m, integer n, integer n1, integer n2, double precision, dimension( ldq, * ) q, integer ldq, double precision, dimension( ldc, * ) c, integer ldc, double precision, dimension( * ) work, integer lwork, integer info)
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
!> 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 Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 161 of file dorm22.f.
Releases
2 releases since Debian 9 (Stretch); the text changed 1 time.