bi modal normal distributions.

greenr 

Google search = very interesting equation indeed / /( $ )( $ )\ \ exp(-((x-4)^2+(y-4)^2)^2/1000) + exp(-((x+4)^2+(y+4)^2)^2/1000) + 0.1exp(-((x+4)^2+(y+4)^2)^2)+0.1exp(-((x-4)^2+(y-4)^2)^2) Attachment 97190 Attachment 97191

Holy Cow...there's more curves in that picture than a highway through the Rocky Mountains.

Rocky Mountains....and a good place to fish and we'd have everything!

greenr 

Google search = very interesting equation indeed / /( $ )( $ )\ \ exp(-((x-4)^2+(y-4)^2)^2/1000) + exp(-((x+4)^2+(y+4)^2)^2/1000) + 0.1exp(-((x+4)^2+(y+4)^2)^2)+0.1exp(-((x-4)^2+(y-4)^2)^2) Attachment 97190 Attachment 97191

I have obtained a slightly different result, there might be two bugs in your graphical interpretation.