Using solvepde with a 'c' coefficient that is a matrix

I want to use pde toolbox to solve an equation of the form

∂/∂x(c1.∂p/∂x)+∂/∂y(c2.∂p/∂y) = f

where c1, c2 are f are functions of x.

I can see that solvepde can handle this, but not sure how I specify the c matrix . Is it a 2x2 with c1 and c2 on the diagonal and zeroes off the diagonal?

Thanks