Shap3d04.dat, 4th 'shape' file for CPO3D
A cylinder of elliptical cross section created with segments of elliptical cross section
A 'squashed' cylinder of elliptical cross section, produced using the 'cre' type of electrode (that is, 'cylindrical rectangle'). A squashed cylinder can also be produced using the stretching option, as illustrated in shap3d02.
The formula that the program uses for the elliptical shape is
(x/a)**2 + (y/b)**2 = 1,
where a and b are the minor and major radii respectively, and where x and y are local orthogonal axes. The area of this ellipse is pi*a*b.
The user has to enter the length of the minor radius and the coordinates of the end points of an elliptical arc. In the present example, a = 1 and the arc is a quadrant from (x,y) = (0,1.5) to (1,0). Reflections are used here to give a complete cylinder.
To obtain only a middle part of the above arc, for example starting at y = 0.5 and finishing at y = 1.0, the equation is solved to give the end points (0.9428,0.5) and (0.7454,1.0). The program will calculate the major radius.
To check that the resulting arc coincides with the full quadrant given above, add a further electrode with the coordinates:
0.9428 0.5 0.5
0.9428 0.5 1.5
0.7454 1.0 1.5
0.7454 1.0 0.5