DORGTR(3F)							    DORGTR(3F)

NAME    [Toc]    [Back]

     DORGTR - generate a real orthogonal matrix	Q which	is defined as the
     product of	n-1 elementary reflectors of order N, as returned by DSYTRD

SYNOPSIS    [Toc]    [Back]

     SUBROUTINE	DORGTR(	UPLO, N, A, LDA, TAU, WORK, LWORK, INFO	)

	 CHARACTER	UPLO

	 INTEGER	INFO, LDA, LWORK, N

	 DOUBLE		PRECISION A( LDA, * ), TAU( * ), WORK( LWORK )

PURPOSE    [Toc]    [Back]

     DORGTR generates a	real orthogonal	matrix Q which is defined as the
     product of	n-1 elementary reflectors of order N, as returned by DSYTRD:

     if	UPLO = 'U', Q =	H(n-1) . . . H(2) H(1),

     if	UPLO = 'L', Q =	H(1) H(2) . . .	H(n-1).

ARGUMENTS    [Toc]    [Back]

     UPLO    (input) CHARACTER*1
	     = 'U': Upper triangle of A	contains elementary reflectors from
	     DSYTRD; = 'L': Lower triangle of A	contains elementary reflectors
	     from DSYTRD.

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

     A	     (input/output) DOUBLE PRECISION array, dimension (LDA,N)
	     On	entry, the vectors which define	the elementary reflectors, as
	     returned by DSYTRD.  On exit, the N-by-N orthogonal matrix	Q.

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

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

     WORK    (workspace/output)	DOUBLE PRECISION array,	dimension (LWORK)
	     On	exit, if INFO =	0, WORK(1) returns the optimal LWORK.

     LWORK   (input) INTEGER
	     The dimension of the array	WORK. LWORK >= max(1,N-1).  For
	     optimum performance LWORK >= (N-1)*NB, where NB is	the optimal
	     blocksize.






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DORGTR(3F)							    DORGTR(3F)



     INFO    (output) INTEGER
	     = 0:  successful exit
	     < 0:  if INFO = -i, the i-th argument had an illegal value
DORGTR(3F)							    DORGTR(3F)

NAME    [Toc]    [Back]

     DORGTR - generate a real orthogonal matrix	Q which	is defined as the
     product of	n-1 elementary reflectors of order N, as returned by DSYTRD

SYNOPSIS    [Toc]    [Back]

     SUBROUTINE	DORGTR(	UPLO, N, A, LDA, TAU, WORK, LWORK, INFO	)

	 CHARACTER	UPLO

	 INTEGER	INFO, LDA, LWORK, N

	 DOUBLE		PRECISION A( LDA, * ), TAU( * ), WORK( LWORK )

PURPOSE    [Toc]    [Back]

     DORGTR generates a	real orthogonal	matrix Q which is defined as the
     product of	n-1 elementary reflectors of order N, as returned by DSYTRD:

     if	UPLO = 'U', Q =	H(n-1) . . . H(2) H(1),

     if	UPLO = 'L', Q =	H(1) H(2) . . .	H(n-1).

ARGUMENTS    [Toc]    [Back]

     UPLO    (input) CHARACTER*1
	     = 'U': Upper triangle of A	contains elementary reflectors from
	     DSYTRD; = 'L': Lower triangle of A	contains elementary reflectors
	     from DSYTRD.

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

     A	     (input/output) DOUBLE PRECISION array, dimension (LDA,N)
	     On	entry, the vectors which define	the elementary reflectors, as
	     returned by DSYTRD.  On exit, the N-by-N orthogonal matrix	Q.

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

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

     WORK    (workspace/output)	DOUBLE PRECISION array,	dimension (LWORK)
	     On	exit, if INFO =	0, WORK(1) returns the optimal LWORK.

     LWORK   (input) INTEGER
	     The dimension of the array	WORK. LWORK >= max(1,N-1).  For
	     optimum performance LWORK >= (N-1)*NB, where NB is	the optimal
	     blocksize.






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DORGTR(3F)							    DORGTR(3F)



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


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