function [f,g,h] = f6(x)
  f = x(1)^4+2*x(2)^4+-3*x(3)^2;
  if nargout > 1
     g = [4*x(1)^3, 8*x(2)^3,-6*x(3)]';
  end;
  if nargout > 2
     h = [12*x(1)^2 0 0; 0 24*x(2)^2 0;  0 0 -6];
  end;