understanding matlab code

This is the EXAMPLE 1.15 in "Fundamentals of Electromagnetics with MATLAB" (by Karl E. Lonngren, 2007):

To plot the vector field A = exp(-(ro/alpha)2)uro
where ro is one of cylindrical coordinates (ro, phi, z) and ruo denotes the unit vector of ro. alpha is cnst.

The attached is code for plot this vector field and its divergence.

I cannot understand what does it mean by following:
Ax(k,s)=exp(-r2(k,s)/alpha.^2)*x(k,s);
Ay(k,s)=exp(-r2(k,s)/alpha.^2)*y(k,s);

Where do they come from?

Why not email the author and ask:

karl-lonngren@uiowa.edu

(The University of Iowa)

Thx. I will have a try...

It seems that these 2-lines code intend to convert the cylindrical coordinates to cartsian coord. and then carry on the derivative on x and y components, respectively.
I'm not sure yet...

Hi "yzou_ua"

can you please email me the .m files for 'fundamentals of electromagnetics with matlab' ?

i need it in urgent.

I will be remain thankful to you :)