Contents
dorghr - generate a real orthogonal matrix Q which is
defined as the product of IHI-ILO elementary reflectors of
order N, as returned by SGEHRD
SUBROUTINE DORGHR(N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO)
INTEGER N, ILO, IHI, LDA, LWORK, INFO
DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*)
SUBROUTINE DORGHR_64(N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO)
INTEGER*8 N, ILO, IHI, LDA, LWORK, INFO
DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*)
F95 INTERFACE
SUBROUTINE ORGHR([N], ILO, IHI, A, [LDA], TAU, [WORK], [LWORK], [INFO])
INTEGER :: N, ILO, IHI, LDA, LWORK, INFO
REAL(8), DIMENSION(:) :: TAU, WORK
REAL(8), DIMENSION(:,:) :: A
SUBROUTINE ORGHR_64([N], ILO, IHI, A, [LDA], TAU, [WORK], [LWORK],
[INFO])
INTEGER(8) :: N, ILO, IHI, LDA, LWORK, INFO
REAL(8), DIMENSION(:) :: TAU, WORK
REAL(8), DIMENSION(:,:) :: A
C INTERFACE
#include <sunperf.h>
void dorghr(int n, int ilo, int ihi, double *a, int lda,
double *tau, int *info);
void dorghr_64(long n, long ilo, long ihi, double *a, long
lda, double *tau, long *info);
dorghr generates a real orthogonal matrix Q which is defined
as the product of IHI-ILO elementary reflectors of order N,
as returned by SGEHRD:
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 SGEHRD. 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 ILO.
A (input/output)
On entry, the vectors which define the elementary
reflectors, as returned by SGEHRD. On exit, the
N-by-N orthogonal 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 SGEHRD.
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