material property setting?

Hi,

I want to customized set the material's property in a 2D model. the material property is a function of position (coordinate-dependent).

e.g.

the conductivity in a 2D model changed through x-direction:

conductivity=f(x), x is the x-coordinate.


How to do that in comsol 4.2?

is there any example in model library?


Thank you very much