redhat man page for dormhr

DORMHR(l)								 )								 DORMHR(l)

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

SYNOPSIS
       SUBROUTINE DORMHR( SIDE, TRANS, M, N, ILO, IHI, A, LDA, TAU, C, LDC, WORK, LWORK, INFO )

	   CHARACTER	  SIDE, TRANS

	   INTEGER	  IHI, ILO, INFO, LDA, LDC, LWORK, M, N

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

PURPOSE
       DORMHR 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 of order nq, with nq = m if SIDE = 'L' and nq = n if SIDE = 'R'. Q is defined as the product of IHI-ILO
       elementary reflectors, as returned by DGEHRD:

       Q = H(ilo) H(ilo+1) . . . H(ihi-1).

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.

       ILO     (input) INTEGER
	       IHI	(input)  INTEGER  ILO  and  IHI must have the same values as in the previous call of DGEHRD. Q is equal to the unit matrix
	       except in the submatrix Q(ilo+1:ihi,ilo+1:ihi).	If SIDE = 'L', then 1 <= ILO <= IHI <= M, if M > 0, and ILO = 1 and IHI = 0, if  M
	       = 0; if SIDE = 'R', then 1 <= ILO <= IHI <= N, if N > 0, and ILO = 1 and IHI = 0, if N = 0.

       A       (input) DOUBLE PRECISION array, dimension
	       (LDA,M) if SIDE = 'L' (LDA,N) if SIDE = 'R' The vectors which define the elementary reflectors, as returned by DGEHRD.

       LDA     (input) INTEGER
	       The leading dimension of the array A.  LDA >= max(1,M) if SIDE = 'L'; LDA >= max(1,N) if SIDE = 'R'.

       TAU     (input) DOUBLE PRECISION array, dimension
	       (M-1)  if  SIDE	=  'L'	(N-1) if SIDE = 'R' TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by
	       DGEHRD.

       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**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) 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

LAPACK version 3.0						   15 June 2000 							 DORMHR(l)