# Animated drawing

### Examples for demonstration

Here you have a list of curves and surfaces plotted with animation. You may either see them directly, or load them into the menu and play with them (i.e. change parameters and options).
1. A plane curve which is progressively drawn. (Cycloid)
2. The Cycloid is the orbit of a point on a circle rolling along a straight line. Here you can see how this is done precisely, with multiple curve plotting.
3. By the same principle, the astroid (cos^3(t),sin^3(t)) is the orbit of a point on a circle of radius 1/4 rolling inside a fixed circle of radius 1.
4. We have also the astroid with 3 arcs.
5. Zooming effect on the curve sin(1/x).
6. A moving tangent along a plane parametric curve (cardioid).
7. The moving tangent along the astroid has a special property: the segment of the tangent cut out by the coordinate axes is of constant length.
8. How an ellipse is drawn by a point on a segment of fixed length with two extremities on the x and y axes respectively.
9. An animation which illustrates the functions sin and cos as vertical and horizontal positions of a moving point on a circle.
10. Rotating and growing trefoil.
11. A space cubic curve. Most simple, but only its movement shows what it is about.
12. A Lissajous figure with rotating phase.
13. The above Lissajous figure is a projection of this space curve. (To see how the projection works, load this formula into the menu and set vertical viewing angle to 0.)
14. Another space curve, a little bit more complicated: hyperbolic spiral.
15. Paraboloïd z=ax2+by2. One sees the surface deform with the variations of a and b.
16. Deformation of hyperboloid x2+y2+az2=1. Vertical.
17. Deformation of hyperboloïde x2+ay2+z2=1. Horizontal.
18. The Moebius band.
19. Riemann surface of two sheets crossing each other.
20. A surface with a singular line, which resembles the precedent one but does not cross.
21. Deformation of one into the other, for the above two surfaces. Without rotation.
22. As above but with rotation at the same time.
23. A plane deforming into a cylinder then back to a plane from the other direction.

If you have produced a particularly interesting plot, please let me know (with descriptions, formulas et options). I might include it into this demo page (of course with credit to you).

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