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dlarfb

 NAME
      DLARFB - apply 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 elemen-
              tary 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 elemen-
              tary 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 elemen-
              tary 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).