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MathGroup Archive 2007

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Re: numerical_solution

  • To: mathgroup at smc.vnet.net
  • Subject: [mg73372] Re: numerical_solution
  • From: "dimitris" <dimmechan at yahoo.com>
  • Date: Wed, 14 Feb 2007 05:22:03 -0500 (EST)
  • References: <eqsa2a$jmb$1@smc.vnet.net>

Your system appeared with extra "=" both in solution1 and solution2
which made it very unreadable.
Please send again your post without them in order to get a reply.

Dimitris

=CF/=C7 j. r. campanha =DD=E3=F1=E1=F8=E5:
> Dear MathGroup people
>
>
> How can I know which is the best numerical solution?
>
>
> w == 6;
> A == 0.1;
> B == 0.17;
> F == 0.501;
>
> solution1 == NDSolve[{x'[t] ==== v[t], v'[t] ==== -(B)*(v[t]) - (A)*(((x[t]))/(1 - (x[t])^2)) + (F)*(Cos[w*t]),x[0] ==== 0.4, v[0] ====
= 0.3}, {x, v}, {t, 260, 270}];
>
> ParametricPlot[Evaluate[{x[t], v[t]} /. solution1], {t, 260, 270}, Frame ->
>  True]
>
>
> OR
>
> solution2 == NDSolve[{x'[t] ==== v[t], v'[t] ==== -(B)*(v[t]) - (A)*(((x[t]))/(1 - (x[t])^2)) + (F)*(Cos[w*t]),x[0] ==== 0.4, v[0] ====
= 0.3}, {x, v}, {t, 260, 270}, Method -> StiffnessSwitching];
>
>
> ParametricPlot[Evaluate[{x[t], v[t]} /. solution2], {t, 260, 270}, Frame ->
>  True]
>
>
>
> Jose R. Campanha
> UNESP-Physics Dpto
> Rio Claro - S=E3o Paulo
> Brasil



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