Re: NDSolve grid

*To*: mathgroup at smc.vnet.net*Subject*: [mg113360] Re: NDSolve grid*From*: schochet123 <schochet123 at gmail.com>*Date*: Mon, 25 Oct 2010 06:40:56 -0400 (EDT)*References*: <i9m83u$jhm$1@smc.vnet.net>

On Oct 20, 10:09 am, pratip <pratip.chakrabo... at gmail.com> wrote: > Here is the code that tries to recover the data about the grid where a > PDE is solved in Mathematica. > {sol, steps} = > Reap[NDSolve[{D[u[t, x, y], t, t] == > D[u[t, x, y], x, x] + D[u[t, x, y], y, y] + Sin[u[t, x, y]], > u[t, -L, y] == u[t, L, y], u[t, x, -L] == u[t, x, L], > u[0, x, y] == Exp[-(x^2 + y^2)], > Derivative[1, 0, 0][u][0, x, y] == 0}, > u, {t, 0, L/2}, {x, -L, L}, {y, -L, L}, > StepMonitor :> Sow[{x, y}]]]; > > I want to see the 2D grid that NDSolve use to discretize the PDE. Is > it possible to do? I found the following trick in the source code of the NDSolveUtilities package: sol=NDSolve[whatever] ifun=u /.sol[[1]] (* where u is the name of (one of ) the dependent variable(s) *) (* This should return an InterpolatingFunction object *) ifun["Coordinates"] (* returns list of lists of coordinates for each independent variable *) (* e.g. {{t0,t1, ... tf},{x1,x2,...,xf}} *) Steve