load (draw); f(x) := a*x^2; astart : 1; amax : 3; amin : -2; astep : 0.5; /* coordinates */ coord : [ head_length = 0.3, color = black, line_width = 1, vector ([-14,0], [28,0]), vector ([0,-14], [0,28]), xaxis = true, xtics_axis = true, yaxis = true, ytics_axis = true, xtics = [-12, 2, 12], ytics = [-12, 2, 12] ]; imagesettings : [ xrange = [-14,14], yrange = [-14,14], user_preamble = ["set noborder"], border = false, dimensions = [500, 500] ]; imagelist : []; alist : []; for a : astart while a < amax step astep do alist : append (alist, [a]); for a : amax while a > amin step (-1) * astep do alist : append (alist, [a]); for a : amin while a < astart step astep do alist : append (alist, [a]); for a in alist do ( labeltext : concat ("a = ", string(a)), image : [gr2d ( coord, imagesettings, label ([labeltext, 6, 12]), explicit (f(x), x, -14, 14) )], imagelist : append (imagelist, image) ); draw ( delay = 100, imagelist, file_name = "aParamQF", terminal = animated_gif );