shell-and-beam example

Happy 2013,

I am trying to understand the (http://www.karamba3d.com/shell-and-beam/) example.

However I don't quiet get it. Does anyone could explain what the formulas are doing ?

sin(z*(sqrt((-5-x)²+(-5-y)²)))

0.15*{1,1,0}*x + y*0.7*x - {0,0,x/4}

Is there any tutorials for karamba except the two available in :

https://www.youtube.com/watch?v=NSpA5uveAaA

https://www.youtube.com/watch?v=D7CRgV1652k

specially for http://www.karamba3d.com/shell-and-beam/ example.

Thank you.