# Tag Info

In any solution to a PDE, whether analytical or numerical, you will always need as many BCs as the number of derivative steps. For examples: $$dY/dt = k Y$$ needs one BC while $$\partial Y/\partial t = k \nabla^2 Y$$ needs three BCs. The second case is germane to your problem. You will need one BC on time $t$ because one derivative is on time. You will need ...