DLARFB (3lapack)

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

SYNOPSIS

  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, * )

PURPOSE

  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).