The plot2D( ) plots animation on 4 ways:
1. click the auto-Axis checkbox.
2. add t into your formula, then click the auto-t checkbox.
3. add the timer(t) into your formula.
4. On a device with a keyboard, try selecting one of the sliders and holding down a cursor key to see the patterns evolve continuously.
The spin3D plots spin of a function, implicit function, parametric function, a spacial curve, and its inverse in 3D graph.
1. a plane in space. 2. a curve in space. 3. cross-section. 4. positive value of a curve spins to make stereo.