CXML
        	    
LAPACK version 3.0
dlarfb(3)

PURPOSE
  DLARFB - applie a real block reflector H or its transpose H' to a real m by
  n matrix C, from either the left or the right

SYNTAX
  SUBROUTINE DLARFB( SIDE, TRANS, DIRECT, STOREV, M, N, K, V, LDV, T, LDT, C,
		     LDC, WORK, LDWORK )

      CHARACTER	     DIRECT, SIDE, STOREV, TRANS

      INTEGER	     K, LDC, LDT, LDV, LDWORK, M, N

      DOUBLE	     PRECISION C( LDC, * ), T( LDT, * ), V( LDV, * ), WORK(
		     LDWORK, * )

DESCRIPTION
  DLARFB applies a real block reflector H or its transpose H' to a real m by
  n matrix C, from either the left or the right.

ARGUMENTS
  SIDE	  (input) CHARACTER*1
	  = 'L': apply H or H' from the Left
	  = 'R': apply H or H' from the Right

  TRANS	  (input) CHARACTER*1
	  = 'N': apply H (No transpose)
	  = 'T': apply H' (Transpose)

  DIRECT  (input) CHARACTER*1
	  Indicates how H is formed from a product of elementary reflectors =
	  'F': H = H(1) H(2) . . . H(k) (Forward)
	  = 'B': H = H(k) . . . H(2) H(1) (Backward)

  STOREV  (input) CHARACTER*1
	  Indicates how the vectors which define the elementary reflectors
	  are stored:
	  = 'C': Columnwise
	  = 'R': Rowwise

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

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

  K	  (input) INTEGER
	  The order of the matrix T (= the number of elementary reflectors
	  whose product defines the block reflector).

  V	  (input) DOUBLE PRECISION array, dimension
	  (LDV,K) if STOREV = 'C' (LDV,M) if STOREV = 'R' and SIDE = 'L'
	  (LDV,N) if STOREV = 'R' and SIDE = 'R' The matrix V. See further
	  details.

  LDV	  (input) INTEGER
	  The leading dimension of the array V.	 If STOREV = 'C' and SIDE =
	  'L', LDV >= max(1,M); if STOREV = 'C' and SIDE = 'R', LDV >=
	  max(1,N); if STOREV = 'R', LDV >= K.

  T	  (input) DOUBLE PRECISION array, dimension (LDT,K)
	  The triangular k by k matrix T in the representation of the block
	  reflector.

  LDT	  (input) INTEGER
	  The leading dimension of the array T. LDT >= K.

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

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

  WORK	  (workspace) DOUBLE PRECISION array, dimension (LDWORK,K)

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