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Re: InterpolatingFunction

  • To: mathgroup at smc.vnet.net
  • Subject: [mg16549] Re: InterpolatingFunction
  • From: "Dale Horton" <daleh>
  • Date: Tue, 16 Mar 1999 04:00:21 -0500
  • Organization: Wolfram Research, Inc.
  • References: <7c5ait$7pr@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Take the InputForm of Sol. The t values are embedded in the
InterpolatingFunction.
For example,

In[1]:=
sol = NDSolve[{Derivative[1][y][x] == y[x], y[1] == 2}, y, {x, 0, 3}]

Out[1]=
{{y -> InterpolatingFunction[{{0., 3.}}, "<>"]}}

In[2]:=
sol[[1, 1, 2, 3, 1]]

Out[2]=
{0., 0.0532966, 0.253442, 0.343912, 0.434382, 0.524852, 0.615322, 0.705792,
  0.751026, 0.796261, 0.841496, 0.886731, 0.942143, 0.960874, 0.979605,
  0.998336, 0.999168, 1., 1.00134, 1.00268, 1.02138, 1.04008, 1.05878,
  1.11402, 1.16926, 1.22449, 1.27973, 1.37335, 1.46697, 1.56059, 1.65421,
  1.74783, 1.89523, 2.04262, 2.19002, 2.33741, 2.48481, 2.63221, 2.8543, 3.}


Virgil Stokes wrote in message <7c5ait$7pr at smc.vnet.net>...
>I have a nonlinear ODE that I solve numerically with NDSolve and
>this of course uses InterpolatingFunction.
>
>Example:
>
> Sol = NDSolve[ {LEE[[1]], LEE[[2]],\[Theta]1[0]==\[Theta]10,
>      \[Theta]1'[0]==\[Theta]1d0, \[Theta]2[0]==\[Theta]20,
>      \[Theta]2'[0]==\[Theta]2d0}, q,{t,0,tfinal}, AccuracyGoal->18,
>    PrecisionGoal->18,
>                                  WorkingPrecision->36,
>    MaxSteps->Infinity] (* Forward dynamics *)
>
>{{\[Theta]1[t]
>        \[Rule]InterpolatingFunction[{{0,
>              2.00000000000000000000000000000000000}},"<>"][t],
>    \[Theta]2[t]
>        \[Rule]InterpolatingFunction[{{0,
>              2.00000000000000000000000000000000000}},"<>"][t]}}
>
>** How can I obtain the complete list of domain values used (all t values)
>     by the InterpolatingFunction?
>
>-- V. Stokes
>
>
>




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