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

DORMRZ(l)					)					DORMRZ(l)

NAME
       DORMRZ  -  overwrite  the general real M-by-N matrix C with  SIDE = 'L' SIDE = 'R' TRANS =
       'N'

SYNOPSIS
       SUBROUTINE DORMRZ( SIDE, TRANS, M, N, K, L, A, LDA, TAU, C, LDC, WORK, LWORK, INFO )

	   CHARACTER	  SIDE, TRANS

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

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

PURPOSE
       DORMRZ overwrites the general real M-by-N matrix C with SIDE = 'L' SIDE = 'R' TRANS = 'N':
       Q * C C * Q TRANS = 'T':      Q**T * C	    C * Q**T

       where Q is a real orthogonal matrix defined as the product of k elementary reflectors

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

       as returned by DTZRZF. Q is of order M if SIDE = 'L' and of order N if SIDE = 'R'.

ARGUMENTS
       SIDE    (input) CHARACTER*1
	       = 'L': apply Q or Q**T from the Left;
	       = 'R': apply Q or Q**T from the Right.

       TRANS   (input) CHARACTER*1
	       = 'N':  No transpose, apply Q;
	       = 'T':  Transpose, apply Q**T.

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

       N       (input) INTEGER
	       The number of columns of the matrix C. N >= 0.

       K       (input) INTEGER
	       The number of elementary reflectors whose product defines the matrix Q.	If SIDE =
	       'L', M >= K >= 0; if SIDE = 'R', N >= K >= 0.

       L       (input) INTEGER
	       The number of columns of the matrix A containing the meaningful part of the House-
	       holder reflectors.  If SIDE = 'L', M >= L >= 0, if SIDE = 'R', N >= L >= 0.

       A       (input) DOUBLE PRECISION array, dimension
	       (LDA,M)	if SIDE = 'L', (LDA,N) if SIDE = 'R' The i-th row must contain the vector
	       which defines the elementary reflector H(i), for i =  1,2,...,k,  as  returned  by
	       DTZRZF  in  the last k rows of its array argument A.  A is modified by the routine
	       but restored on exit.

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

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

       C       (input/output) DOUBLE PRECISION array, dimension (LDC,N)
	       On  entry,  the	M-by-N	matrix	C.  On exit, C is overwritten by Q*C or Q**H*C or
	       C*Q**H or C*Q.

       LDC     (input) INTEGER
	       The leading dimension of the array C. LDC >= max(1,M).

       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.  If SIDE = 'L', LWORK >= max(1,N); if SIDE = 'R',
	       LWORK >= max(1,M).  For optimum performance LWORK >= N*NB if SIDE = 'L', and LWORK
	       >= M*NB if SIDE = 'R', 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 had an illegal value

FURTHER DETAILS
       Based on contributions by
	 A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA

LAPACK version 3.0			   15 June 2000 				DORMRZ(l)


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