cungbr - generate one of the complex unitary matrices Q or P**H determined by CGEBRD when reducing a complex matrix A to bidiagonal form
SUBROUTINE CUNGBR( VECT, M, N, K, A, LDA, TAU, WORK, LWORK, INFO) CHARACTER * 1 VECT COMPLEX A(LDA,*), TAU(*), WORK(*) INTEGER M, N, K, LDA, LWORK, INFO
SUBROUTINE CUNGBR_64( VECT, M, N, K, A, LDA, TAU, WORK, LWORK, INFO) CHARACTER * 1 VECT COMPLEX A(LDA,*), TAU(*), WORK(*) INTEGER*8 M, N, K, LDA, LWORK, INFO
SUBROUTINE UNGBR( VECT, M, [N], K, A, [LDA], TAU, [WORK], [LWORK], * [INFO]) CHARACTER(LEN=1) :: VECT COMPLEX, DIMENSION(:) :: TAU, WORK COMPLEX, DIMENSION(:,:) :: A INTEGER :: M, N, K, LDA, LWORK, INFO
SUBROUTINE UNGBR_64( VECT, M, [N], K, A, [LDA], TAU, [WORK], [LWORK], * [INFO]) CHARACTER(LEN=1) :: VECT COMPLEX, DIMENSION(:) :: TAU, WORK COMPLEX, DIMENSION(:,:) :: A INTEGER(8) :: M, N, K, LDA, LWORK, INFO
#include <sunperf.h>
void cungbr(char vect, int m, int n, int k, complex *a, int lda, complex *tau, int *info);
void cungbr_64(char vect, long m, long n, long k, complex *a, long lda, complex *tau, long *info);
cungbr generates one of the complex unitary matrices Q or P**H
determined by CGEBRD when reducing a complex matrix A to bidiagonal
form: A = Q * B * P**H. Q and P**H are defined as products of
elementary reflectors H(i)
or G(i)
respectively.
If VECT = 'Q', A is assumed to have been an M-by-K matrix, and Q is of order M:
if m >= k, Q = H(1)
H(2)
. . . H(k)
and CUNGBR returns the first n
columns of Q, where m >= n >= k;
if m < k, Q = H(1)
H(2)
. . . H(m-1)
and CUNGBR returns Q as an
M-by-M matrix.
If VECT = 'P', A is assumed to have been a K-by-N matrix, and P**H is of order N:
if k < n, P**H = G(k)
. . . G(2)
G(1)
and CUNGBR returns the first m
rows of P**H, where n >= m >= k;
if k >= n, P**H = G(n-1)
. . . G(2)
G(1)
and CUNGBR returns P**H as
an N-by-N matrix.
= 'Q': generate Q;
= 'P': generate P**H.
TAU(i)
must contain the scalar factor of the elementary
reflector H(i)
or G(i), which determines Q or P**H, as
returned by CGEBRD in its array argument TAUQ or TAUP.
WORK(1)
returns the optimal LWORK.
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.
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value