Black and white display of a tridimensional function [Visualisation noir et blanc d'une fonction tridimensionnelle].
A tridimensional function F(x,y,z) can be visualized using a regular mesh.
Each of its (x,y,z) nodes is represented by means of a lighted sphere whose
radius and {R,G,B} colors can display four different scalar values. For
this particular picture, this four parameters as chosen as follows: