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LAPACK version 3.0
sopgtr(3)

PURPOSE
  SOPGTR - 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 SSPTRD
  using packed storage

SYNTAX
  SUBROUTINE SOPGTR( UPLO, N, AP, TAU, Q, LDQ, WORK, INFO )

      CHARACTER	     UPLO

      INTEGER	     INFO, LDQ, N

      REAL	     AP( * ), Q( LDQ, * ), TAU( * ), WORK( * )

DESCRIPTION
  SOPGTR 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 SSPTRD 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
	  SSPTRD; = 'L': Lower triangular packed storage used in previous
	  call to SSPTRD.

  N	  (input) INTEGER
	  The order of the matrix Q. N >= 0.

  AP	  (input) REAL array, dimension (N*(N+1)/2)
	  The vectors which define the elementary reflectors, as returned by
	  SSPTRD.

  TAU	  (input) REAL array, dimension (N-1)
	  TAU(i) must contain the scalar factor of the elementary reflector
	  H(i), as returned by SSPTRD.

  Q	  (output) REAL 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) REAL array, dimension (N-1)

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