How can I solve the following PDE problem in MATLAB. I do not see how to formulate it in a form suitable for the pdepe function.

C * Dusubi/Dt = x^-2 * D/Dx(x^2 * C * Dsubi * Dusubi/Dx) - N * Dusubi/Dx i = 1 to 6

where

N = Sum(i=1:6)[C * Dsubi * Dusubi/Dx) * Msubi^0.5] / Sum(i=1:6)[usubi * Msubi ^0.5] Msubi, C, and Dsubi are constants

Left boundary condition: Dui/Dx(0,t) = 0 for i = 1 to 6

Right boundary condition: - C * Di * Dui/Dx + N * ui + p(ui) = 0 for i = 1 to 6

The problem I have is that I cannot express the right boundary coondition in the form that MATLAB [p1,q1,pr,qr] = bcfun(x1,u1,xr,ur,t) expects, which is:

p(x,t,u) + q(x,t) * f(x,t,u,Du/Dx) = 0.

Any help would be greatly appreciated.

Thanks,

Doug