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Re: AbsoluteOptions and NDSolve

  • To: mathgroup at smc.vnet.net
  • Subject: [mg123884] Re: AbsoluteOptions and NDSolve
  • From: Bob Hanlon <hanlonr357 at gmail.com>
  • Date: Tue, 27 Dec 2011 05:38:20 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <201112262230.RAA20909@smc.vnet.net>

The output of NDSolve does not have options. Use StepMonitor

xList = Reap[nds = NDSolve[
       {y'[x] == y[x] Cos[x + y[x]], y[0] == 1},
       y, {x, 0, 30}, StepMonitor :> Sow[x]][[1]]][[2, 1]];

steps=Differences[xList];

Take[steps,10]

{0.00017069, 0.00034138, 0.00034138, 0.00034138, 0.0034138, \
0.0034138, 0.0034138, 0.0034138, 0.0227572, 0.0227572}


Bob Hanlon

On Mon, Dec 26, 2011 at 5:30 PM, Snark <gadior at gmail.com> wrote:
> Hi,
>
> I am perplexed by the behavior of AbsoluteOptions on NDSolve. I tried
> getting the actual value of StartingStepSize and got something weird.
>
> In[]:= AbsoluteOptions[NDSolve[eqSys, {c[x, t], T[x, t]}, {x, 0, xb},
> {t, 0,1}]],StartingStepSize]
> Out[]:= {{AbsoluteOptions[c[x,t]->InterpolatingFunction[{{0.,5.*10^-6},
> {0.,1.}},<>][x,t],StartingStepSize],AbsoluteOptions[T[x,t]-
>>InterpolatingFunction[{{0.,5.*10^-6},{0.,1.}},<>]
> [x,t],StartingStepSize]}}
>
> Isn't there a way to fetch absolute options from NDSolve?
>
> Thanks in advance
>
>



-- 
Bob Hanlon



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