  n = 1400;
  nonzer = 7;
  lambda = 20;
  niter = 15;
  nz = n * ( nonzer + 1 ) * ( nonzer + 1 ) + n * ( nonzer + 2 );

  A = sprand ( n, n, 0.5 * nz / n^2, codistributor ( ) );
  A = 0.5 * ( A + A' );

  I = speye ( n, codistributor ( ) );
  A = A - lambda * I;

  x = ones ( n, 1 );

  for iter = 1 : niter
    [ z, rnorm ] = cgit ( A, x );
    zeta = lambda + 1 / ( x' * z )
    x = z / norm ( z );
  end

