
DOPGTR(l) ) DOPGTR(l)
NAME
DOPGTR  generate a real orthogonal matrix Q which is defined as the product of n1 ele
mentary 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 UPLO
INTEGER INFO, LDQ, N
DOUBLE PRECISION AP( * ), Q( LDQ, * ), TAU( * ), WORK( * )
PURPOSE
DOPGTR generates a real orthogonal matrix Q which is defined as the product of n1 elemen
tary reflectors H(i) of order n, as returned by DSPTRD using packed storage: if UPLO =
'U', Q = H(n1) . . . H(2) H(1),
if UPLO = 'L', Q = H(1) H(2) . . . H(n1).
ARGUMENTS
UPLO (input) CHARACTER*1
= 'U': Upper triangular packed storage used in previous call to DSPTRD; = 'L':
Lower triangular packed storage used in previous call to DSPTRD.
N (input) INTEGER
The order of the matrix Q. N >= 0.
AP (input) DOUBLE PRECISION array, dimension (N*(N+1)/2)
The vectors which define the elementary reflectors, as returned by DSPTRD.
TAU (input) DOUBLE PRECISION array, dimension (N1)
TAU(i) must contain the scalar factor of the elementary reflector H(i), as
returned by DSPTRD.
Q (output) DOUBLE PRECISION array, dimension (LDQ,N)
The NbyN orthogonal matrix Q.
LDQ (input) INTEGER
The leading dimension of the array Q. LDQ >= max(1,N).
WORK (workspace) DOUBLE PRECISION array, dimension (N1)
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = i, the ith argument had an illegal value
LAPACK version 3.0 15 June 2000 DOPGTR(l) 
