XSI, ICE, Maths, Cassini Oval

for details see here http://en.wikipedia.org/wiki/Cassini_... and was inspired to have a go when saw this https://vimeo.com/1346421 think this guys is much cleaner gradient math than my ICE tree. the scene can be downloaded from here. https://docs.google.com/open?id=0B0WD... really simple just all the distances between particles and the Q nulls 1 - 4 multiplied together.. thats it.