I use Mathematica NDSolve to numerically solve V(x,t) and export the numerical values of V(x,t) at each x and t into an external csv file. I find Mathematica only numerically give results with step size of 1 in both x and t. However, I want a finer grid of the numerical results, for example, 0, 0.01, 0.02, … , M in the x-dimension. I tried to add MaxStepSize→0.1 in the NDSolver, but it gives errors and seems not solving finer grid of x in the csv file. NDSolve::ndsz: At t == 95.86748044587323`, step size is effectively zero; singularity or stiff system suspected. >>
My question: what is the correct way to get numerical matrix on V(x,t) on a finer x? The relevant code is in export.nb