Contents
cungql - generate an M-by-N complex matrix Q with orthonor-
mal columns,
SUBROUTINE CUNGQL(M, N, K, A, LDA, TAU, WORK, LWORK, INFO)
COMPLEX A(LDA,*), TAU(*), WORK(*)
INTEGER M, N, K, LDA, LWORK, INFO
SUBROUTINE CUNGQL_64(M, N, K, A, LDA, TAU, WORK, LWORK, INFO)
COMPLEX A(LDA,*), TAU(*), WORK(*)
INTEGER*8 M, N, K, LDA, LWORK, INFO
F95 INTERFACE
SUBROUTINE UNGQL(M, [N], [K], A, [LDA], TAU, [WORK], [LWORK], [INFO])
COMPLEX, DIMENSION(:) :: TAU, WORK
COMPLEX, DIMENSION(:,:) :: A
INTEGER :: M, N, K, LDA, LWORK, INFO
SUBROUTINE UNGQL_64(M, [N], [K], A, [LDA], TAU, [WORK], [LWORK],
[INFO])
COMPLEX, DIMENSION(:) :: TAU, WORK
COMPLEX, DIMENSION(:,:) :: A
INTEGER(8) :: M, N, K, LDA, LWORK, INFO
C INTERFACE
#include <sunperf.h>
void cungql(int m, int n, int k, complex *a, int lda, com-
plex *tau, int *info);
void cungql_64(long m, long n, long k, complex *a, long lda,
complex *tau, long *info);
cungql generates an M-by-N complex matrix Q with orthonormal
columns, which is defined as the last N columns of a product
of K elementary reflectors of order M
Q = H(k) . . . H(2) H(1)
as returned by CGEQLF.
M (input) The number of rows of the matrix Q. M >= 0.
N (input) The number of columns of the matrix Q. M >= N >=
0.
K (input) The number of elementary reflectors whose product
defines the matrix Q. N >= K >= 0.
A (input/output)
On entry, the (n-k+i)-th column must contain the
vector which defines the elementary reflector
H(i), for i = 1,2,...,k, as returned by CGEQLF in
the last k columns of its array argument A. On
exit, the M-by-N matrix Q.
LDA (input)
The first dimension of the array A. LDA >=
max(1,M).
TAU (input)
TAU(i) must contain the scalar factor of the ele-
mentary reflector H(i), as returned by CGEQLF.
WORK (workspace)
On exit, if INFO = 0, WORK(1) returns the optimal
LWORK.
LWORK (input)
The dimension of the array WORK. LWORK >=
max(1,N). For optimum performance LWORK >= N*NB,
where NB is the optimal blocksize.
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 (output)
= 0: successful exit
< 0: if INFO = -i, the i-th argument has an ille-
gal value