redhat man page for dopgtr

DOPGTR(l)								 )								 DOPGTR(l)

NAME
       DOPGTR  -  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	  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 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) 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 (N-1)
	       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 N-by-N orthogonal matrix Q.

       LDQ     (input) INTEGER
	       The leading dimension of the array Q. LDQ >= max(1,N).

       WORK    (workspace) DOUBLE PRECISION array, dimension (N-1)

       INFO    (output) INTEGER
	       = 0:  successful exit
	       < 0:  if INFO = -i, the i-th argument had an illegal value

LAPACK version 3.0						   15 June 2000 							 DOPGTR(l)