Drawing using MATLAB "HELP".

Hi...

I want to draw a spherical shell with inner and outer radii equal to a & b, centered at (x,y,z).. and fill it with a dielectric material with permittivity
( ε = ε0×εr ).

The problem is in defining the spherical shape.

and this spherical shell is inside a 3D Cartesian Yee grid.

Thanx in advance.

Dennis Sullivan FDTD book have such a code in chapter 4.

I saw it...

not exactly what I need...

Thanx.