plot3d(x^4-2*x^2*y+y^2, [x, -2, 2], [y, 0, 10]);

	contour_plot(x^4-2*x^2*y+y^2, [x, -2, 2], [y, 0, 10]);

contour_plot(x^4-2*x^2*y+y^2, [x, -2, 2], [y, 0, 10], [legend,false], [gnuplot_preamble, "set cntrparam levels 10"]);

	plot3d(x^4-2*x^2*y+y^2,[x,-2,2],[y,-0,10],[legend, false], [gnuplot_preamble,"set contour;set cntrparam levels 20"]);

plot3d(x^4-2*x^2*y+y^2,[x,-2,2],[y,-0,10],[legend, false], [gnuplot_preamble,"set view map;set contour;set cntrparam levels 20"]);