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slarf

 NAME
      SLARF - apply a real elementary reflector H to a real m by n
      matrix C, from either the left or the right

 SYNOPSIS
      SUBROUTINE SLARF( SIDE, M, N, V, INCV, TAU, C, LDC, WORK )

          CHARACTER     SIDE

          INTEGER       INCV, LDC, M, N

          REAL          TAU

          REAL          C( LDC, * ), V( * ), WORK( * )

 PURPOSE
      SLARF applies a real elementary reflector H to a real m by n
      matrix C, from either the left or the right. H is
      represented in the form

            H = I - tau * v * v'

      where tau is a real scalar and v is a real vector.

      If tau = 0, then H is taken to be the unit matrix.

 ARGUMENTS
      SIDE    (input) CHARACTER*1
              = 'L': form  H * C
              = 'R': form  C * H

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

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

      V       (input) REAL array, dimension
              (1 + (M-1)*abs(INCV)) if SIDE = 'L' or (1 + (N-
              1)*abs(INCV)) if SIDE = 'R' The vector v in the
              representation of H. V is not used if TAU = 0.

      INCV    (input) INTEGER
              The increment between elements of v. INCV <> 0.

      TAU     (input) REAL
              The value tau in the representation of H.

      C       (input/output) REAL array, dimension (LDC,N)
              On entry, the m by n matrix C.  On exit, C is
              overwritten by the matrix H * C if SIDE = 'L', or C

              * H if SIDE = 'R'.

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

      WORK    (workspace) REAL array, dimension
              (N) if SIDE = 'L' or (M) if SIDE = 'R'