Contents
zunghr - generate a complex unitary matrix Q which is
defined as the product of IHI-ILO elementary reflectors of
order N, as returned by CGEHRD
SUBROUTINE ZUNGHR(N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO)
DOUBLE COMPLEX A(LDA,*), TAU(*), WORK(*)
INTEGER N, ILO, IHI, LDA, LWORK, INFO
SUBROUTINE ZUNGHR_64(N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO)
DOUBLE COMPLEX A(LDA,*), TAU(*), WORK(*)
INTEGER*8 N, ILO, IHI, LDA, LWORK, INFO
F95 INTERFACE
SUBROUTINE UNGHR([N], ILO, IHI, A, [LDA], TAU, [WORK], [LWORK], [INFO])
COMPLEX(8), DIMENSION(:) :: TAU, WORK
COMPLEX(8), DIMENSION(:,:) :: A
INTEGER :: N, ILO, IHI, LDA, LWORK, INFO
SUBROUTINE UNGHR_64([N], ILO, IHI, A, [LDA], TAU, [WORK], [LWORK],
[INFO])
COMPLEX(8), DIMENSION(:) :: TAU, WORK
COMPLEX(8), DIMENSION(:,:) :: A
INTEGER(8) :: N, ILO, IHI, LDA, LWORK, INFO
C INTERFACE
#include <sunperf.h>
void zunghr(int n, int ilo, int ihi, doublecomplex *a, int
lda, doublecomplex *tau, int *info);
void zunghr_64(long n, long ilo, long ihi, doublecomplex *a,
long lda, doublecomplex *tau, long *info);
zunghr generates a complex unitary matrix Q which is defined
as the product of IHI-ILO elementary reflectors of order N,
as returned by CGEHRD:
Q = H(ilo) H(ilo+1) . . . H(ihi-1).
N (input) The order of the matrix Q. N >= 0.
ILO (input)
ILO and IHI must have the same values as in the
previous call of CGEHRD. Q is equal to the unit
matrix except in the submatrix
Q(ilo+1:ihi,ilo+1:ihi). 1 <= ILO <= IHI <= N, if
N > 0; ILO=1 and IHI=0, if N=0.
IHI (input)
See the description of IHI.
A (input/output)
On entry, the vectors which define the elementary
reflectors, as returned by CGEHRD. On exit, the
N-by-N unitary matrix Q.
LDA (input)
The leading dimension of the array A. LDA >=
max(1,N).
TAU (input)
TAU(i) must contain the scalar factor of the ele-
mentary reflector H(i), as returned by CGEHRD.
WORK (workspace)
On exit, if INFO = 0, WORK(1) returns the optimal
LWORK.
LWORK (input)
The dimension of the array WORK. LWORK >= IHI-ILO.
For optimum performance LWORK >= (IHI-ILO)*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 had an
illegal value