x and y are inverted versions of each other, z is tan( x ); no step colouring all color is entirely natural. (in most cases this would be pure white, but in this case it produces and interesting cyan/magenta)
This particular variation [m7] has some even stranger variations, in particular by modifying the operators in x and y to multiplication rather than division we can produce:
Full details and more examples can be found at webr3.org/blog.
for( i in 0...PARTICLES ) {
a = (360/PARTICLES)*i;
r = (i/PARTICLES) * Math.PI;
x = Math.sin(a) / Math.cos(r);
y = Math.cos(a) / Math.sin(r);
z = Math.tan( x );
}