Post it in the "Differential Equations" forum, as the Black-Scholes Model is an extremely popular PDE. As a reminder, the BSM is: [itex] \frac{\partial V}{\partial t} + \frac{1}{2} \sigma^2 S^2 \frac{\partial^2V}{\partial S^2} + rS \frac{\partial V}{\partial S} - rV = 0 [/itex]