zungqr(3P) Sun Performance Library zungqr(3P)NAMEzungqr - generate an M-by-N complex matrix Q with orthonormal columns,
SYNOPSIS
SUBROUTINE ZUNGQR(M, N, K, A, LDA, TAU, WORKIN, LWORKIN, INFO)
DOUBLE COMPLEX A(LDA,*), TAU(*), WORKIN(*)
INTEGER M, N, K, LDA, LWORKIN, INFO
SUBROUTINE ZUNGQR_64(M, N, K, A, LDA, TAU, WORKIN, LWORKIN, INFO)
DOUBLE COMPLEX A(LDA,*), TAU(*), WORKIN(*)
INTEGER*8 M, N, K, LDA, LWORKIN, INFO
F95 INTERFACE
SUBROUTINE UNGQR(M, [N], [K], A, [LDA], TAU, [WORKIN], [LWORKIN],
[INFO])
COMPLEX(8), DIMENSION(:) :: TAU, WORKIN
COMPLEX(8), DIMENSION(:,:) :: A
INTEGER :: M, N, K, LDA, LWORKIN, INFO
SUBROUTINE UNGQR_64(M, [N], [K], A, [LDA], TAU, [WORKIN], [LWORKIN],
[INFO])
COMPLEX(8), DIMENSION(:) :: TAU, WORKIN
COMPLEX(8), DIMENSION(:,:) :: A
INTEGER(8) :: M, N, K, LDA, LWORKIN, INFO
C INTERFACE
#include <sunperf.h>
void zungqr(int m, int n, int k, doublecomplex *a, int lda, doublecom‐
plex *tau, int *info);
void zungqr_64(long m, long n, long k, doublecomplex *a, long lda, dou‐
blecomplex *tau, long *info);
PURPOSEzungqr generates an M-by-N complex matrix Q with orthonormal columns,
which is defined as the first N columns of a product of K elementary
reflectors of order M
Q = H(1)H(2) . . . H(k)
as returned by ZGEQRF.
ARGUMENTS
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 i-th column must contain the vector which
defines the elementary reflector H(i), for i = 1,2,...,k, as
returned by ZGEQRF in the first k columns of its array argu‐
ment 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 elementary
reflector H(i), as returned by ZGEQRF.
WORKIN (workspace)
On exit, if INFO = 0, WORKIN(1) returns the optimal LWORKIN.
LWORKIN (input)
The dimension of the array WORKIN. LWORKIN >= max(1,N). For
optimum performance LWORKIN >= N*NB, where NB is the optimal
blocksize.
If LWORKIN = -1, then a workspace query is assumed; the rou‐
tine only calculates the optimal size of the WORKIN array,
returns this value as the first entry of the WORKIN array,
and no error message related to LWORKIN is issued by XERBLA.
INFO (output)
= 0: successful exit
< 0: if INFO = -i, the i-th argument has an illegal value
6 Mar 2009 zungqr(3P)