pdepe: Boundary condition for Fisher-like equation

Hello,

I have a question about how I should set up the boundary condition correctly when solving a Fisher-like equation with pdepe. Please see attached for the equation and the initial condition.

When I set up the boundary condition for U(-inf,t) = U(inf,t) = 0, that is pl = uL; ql = 0; pr = uR; qr = 0; then pdepe forces the solution to be zero at the edges of my domain, which is not correct.

Could you help me with this?

Thank you! Satomi

How should I set up the boundary condition?

Thank you! Satomi