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RedHat 9 (Linux i386) - man page for dorgrq (redhat section l)

DORGRQ(l)					)					DORGRQ(l)

NAME
       DORGRQ - generate an M-by-N real matrix Q with orthonormal rows,

SYNOPSIS
       SUBROUTINE DORGRQ( M, N, K, A, LDA, TAU, WORK, LWORK, INFO )

	   INTEGER	  INFO, K, LDA, LWORK, M, N

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

PURPOSE
       DORGRQ  generates  an  M-by-N real matrix Q with orthonormal rows, which is defined as the
       last M rows of a product of K elementary reflectors of order N

	     Q	=  H(1) H(2) . . . H(k)

       as returned by DGERQF.

ARGUMENTS
       M       (input) INTEGER
	       The number of rows of the matrix Q. M >= 0.

       N       (input) INTEGER
	       The number of columns of the matrix Q. N >= M.

       K       (input) INTEGER
	       The number of elementary reflectors whose product defines the matrix Q. M >= K  >=
	       0.

       A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
	       On  entry, the (m-k+i)-th row must contain the vector which defines the elementary
	       reflector H(i), for i = 1,2,...,k, as returned by DGERQF in the last k rows of its
	       array argument A.  On exit, the M-by-N matrix Q.

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

       TAU     (input) DOUBLE PRECISION array, dimension (K)
	       TAU(i)  must  contain  the  scalar  factor  of  the  elementary reflector H(i), as
	       returned by DGERQF.

       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,M).  For optimum performance LWORK
	       >= M*NB, where NB is the optimal blocksize.

	       If  LWORK = -1, then a workspace query is assumed; the routine only calculates the
	       optimal size of the WORK array, returns this value as the first entry of the  WORK
	       array, and no error message related to LWORK is issued by XERBLA.

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

LAPACK version 3.0			   15 June 2000 				DORGRQ(l)


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