[Chageset]: Add the spaugment function

[Ben Abbott]

On Apr 2, 2008, at 1:12 PM, David Bateman wrote:
> Another easy function to implement. The help string and the example  
> took
> longer to write :-)
>
> D.

David, I'm getting a failure with this one.

Is there reason for concern?

In event it is important, I built with SuiteSparse 3.1.0.

octave:5> test spaugment
   ***** test
  m = 11; n = 10; mn = max(m ,n);
  a = spdiags ([ones(mn,1), 10*ones(mn,1), -ones(mn,1)],[-1,0,1], m, n);
  x0 = a \ ones (m,1);
  s = spaugment (a);
  [L, U, P, Q] = lu (s);
  x1 = Q * (U \ (L \ (P  * [ones(m,1); zeros(n,1)])));
  x1 = x1(end - n + 1 : end);
  assert (x1, x0, 1e-10)
!!!!! test failed
error: assert (x1,x0,1e-10) expected
    0.109902
    0.099020
    0.100097
    0.099990
    0.100001
    0.100000
    0.099990
    0.099990
    0.099020
    0.099020
but got
    0.109902
    0.099020
    0.100097
    0.099990
    0.100001
    0.100000
    0.099990
    0.099990
    0.099020
    0.099020
maximum absolute error 1.655e-07 exceeds tolerance 1e-10

Ben