for t fixed, what is the FF++ instructions to obtain the graphic in 2 D with Gnuplot or Paraview, of U(x,y,t) for all (x,y)?
Please
I found this instruction

int[int] Order = [1];string DataName = "u";savevtk("u.vtu", Th, u, dataname=DataName, order=Order);

but in this example there is no t, so we how we obtain the graphic en 2D of U(t,x,y) for t fixed?