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Re: NDSolve output without interpolating function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg124213] Re: NDSolve output without interpolating function
  • From: Bob Hanlon <hanlonr357 at gmail.com>
  • Date: Sat, 14 Jan 2012 02:52:05 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <201201130951.EAA16470@smc.vnet.net>

You could generate a Table of points using the interpolating function;
however, it would be difficult to sample the function at the best
values. If you let Mathematica Plot the function then you can leverage
its sampling algorithm.

Clear[nDSolve]

nDSolve[eqn_, depVar_Symbol, iter_List, opts_: {}] :=

 Module[{sol, plt, pts},
  sol = depVar /. NDSolve[eqn, depVar, iter,
      FilterRules[opts, Options[NDSolve]]][[1]];
  plt = Plot[sol[iter[[1]]], iter,
    Evaluate[FilterRules[opts, Options[Plot]]]];
  pts = Cases[plt, Line[pts_] :> pts, Infinity][[1]];
  {sol, plt, pts}]

sol = nDSolve[{y'[x] == y[x] Cos[x + y[x]], y[0] == 1},
   y, {x, 0, 30}, PlotRange -> All];

The result includes the interpolating function

Plot[sol[[1]][x], {x, 0, 30}, PlotRange -> All]

the plot used to capture the points

Show[sol[[2]]]

and the list of points

ListLinePlot[sol[[3]], PlotRange -> All]


Bob Hanlon


On Fri, Jan 13, 2012 at 4:51 AM, william cuervo <wfcuervo at gmail.com> wrote:
> Hi!
>
> Is there any way that NDSolve presents the output as a set of data instead
> of as an interpolating function?
>
>
> Thanks!



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