redhat man page for sormqr

SORMQR(l)								 )								 SORMQR(l)

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

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

	   CHARACTER	  SIDE, TRANS

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

	   REAL 	  A( LDA, * ), C( LDC, * ), TAU( * ), WORK( * )

PURPOSE
       SORMQR 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 SGEQRF. 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.

       A       (input) REAL array, dimension (LDA,K)
	       The i-th column must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned  by	SGEQRF	in
	       the first k columns 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.  If SIDE = 'L', LDA >= max(1,M); if SIDE = 'R', LDA >= max(1,N).

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

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

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

       WORK    (workspace/output) REAL 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

LAPACK version 3.0						   15 June 2000 							 SORMQR(l)