dopgtr(3P) Sun Performance Library dopgtr(3P)NAMEdopgtr - generate a real orthogonal matrix Q which is defined as the
product of n-1 elementary reflectors H(i) of order n, as returned by
DSPTRD using packed storage
SYNOPSIS
SUBROUTINE DOPGTR(UPLO, N, AP, TAU, Q, LDQ, WORK, INFO)
CHARACTER * 1 UPLO
INTEGER N, LDQ, INFO
DOUBLE PRECISION AP(*), TAU(*), Q(LDQ,*), WORK(*)
SUBROUTINE DOPGTR_64(UPLO, N, AP, TAU, Q, LDQ, WORK, INFO)
CHARACTER * 1 UPLO
INTEGER*8 N, LDQ, INFO
DOUBLE PRECISION AP(*), TAU(*), Q(LDQ,*), WORK(*)
F95 INTERFACE
SUBROUTINE OPGTR(UPLO, [N], AP, TAU, Q, [LDQ], [WORK], [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER :: N, LDQ, INFO
REAL(8), DIMENSION(:) :: AP, TAU, WORK
REAL(8), DIMENSION(:,:) :: Q
SUBROUTINE OPGTR_64(UPLO, [N], AP, TAU, Q, [LDQ], [WORK], [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER(8) :: N, LDQ, INFO
REAL(8), DIMENSION(:) :: AP, TAU, WORK
REAL(8), DIMENSION(:,:) :: Q
C INTERFACE
#include <sunperf.h>
void dopgtr(char uplo, int n, double *ap, double *tau, double *q, int
ldq, int *info);
void dopgtr_64(char uplo, long n, double *ap, double *tau, double *q,
long ldq, long *info);
PURPOSEdopgtr generates a real orthogonal matrix Q which is defined as the
product of n-1 elementary reflectors H(i) of order n, as returned by
DSPTRD using packed storage:
if UPLO = 'U', Q = H(n-1) . . . H(2)H(1),
if UPLO = 'L', Q = H(1)H(2) . . . H(n-1).
ARGUMENTS
UPLO (input)
= 'U': Upper triangular packed storage used in previous call
to DSPTRD; = 'L': Lower triangular packed storage used in
previous call to DSPTRD.
N (input) The order of the matrix Q. N >= 0.
AP (input)
The vectors which define the elementary reflectors, as
returned by DSPTRD.
TAU (input)
TAU(i) must contain the scalar factor of the elementary
reflector H(i), as returned by DSPTRD.
Q (output)
The N-by-N orthogonal matrix Q.
LDQ (input)
The leading dimension of the array Q. LDQ >= max(1,N).
WORK (workspace)
dimension(N-1)
INFO (output)
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
6 Mar 2009 dopgtr(3P)
