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**T

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

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

          SIDE is CHARACTER*1
          = 'L': form  H * C
          = 'R': form  C * H

          M is INTEGER
          The number of rows of the matrix C.

          N is INTEGER
          The number of columns of the matrix C.

          V is 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 is INTEGER
          The increment between elements of v. INCV <> 0.

          TAU is REAL
          The value tau in the representation of H.

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

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