Now that you have a surface, lets make it more interactive. Suppose you are interested in the family of surfaces
f(x,y) = x^{3}  ax  y^{2} for various values of a. We can make a slider for the value of a so that changing the slider changes the surface. To do this, edit the function to beFunction {x y} { let z = x^3  a x  y^2 }and below this add the lineSlider a 1 1 0This declares a slider tied to the variablea
whose values run from 1 to 1 and is set initially to 0. When you hit theUpdate
button, the slider will appear in its own window. First, move this to a convenient location, then change the value of the slider by dragging it; when you let go, the surface should be updated to reflect the new value ofa
.^{1}Note that the values of sliders can be used almost anywhere. For instance, you can change the domain to
Domain {{1 1 n} {1 1 n}} Slider n 1 20 10 resolution 1in order to have the number of subdivisions be controlled by a slider. Here, the resolution of the slider is set to 1 so that it will take on only integer values.
^{1} 


