Help me to use PDEPE command?

Hello all.

I want to solve a partial differential equation using PDEPE.

The partial differential equation is given by du/dt=D*x^(-2)d/dr(x^(2)du/dx)+p*u -K(t)*u

I think %function

function [c,f,s] = pdex1pde(x,t,u,DuDx)

c = 1;

f = D*DuDx;

s = (p-K(t))*u

 but I am not sure about s=(p-K(t))*u.

Would you let me know the right function?

Thank you very much.