function f = luflop (L, U)						    %#ok
  %LUFLOP given L and U, computes # of flops required to compute them
  %
  % Example:
  % f = luflop (L, U)
  %
  % Given an LU factorization, compute how many flops took to compute it.  This
  % is the same as (assuming U has a zero-free diagonal):
  %
  %   Lnz = full (sum (spones (L))) - 1 ;
  %   Unz = full (sum (spones (U')))' - 1 ;
  %   f = 2*Lnz*Unz + sum (Lnz) ;
  %
  % except that no extra workspace is allocated for spones (L) and spones (U).
  % L and U must be sparse.
  %
  % Note: the above expression has a subtle undercount when exact numerical
  % cancelation occurs.  Try [L,U,P] = lu (sparse (ones (10))) and then
  % luflop (L,U).
  %
  % See also LU
  
  % Copyright 1995-2007 by Timothy A. Davis.
  
  help luflop
  error ('luflop mexFunction not found!  Use umfpack_make to compile luflop.') ;