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MathGroup Archive 2004

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Re: Error with NDSolve

  • To: mathgroup at
  • Subject: [mg50956] Re: Error with NDSolve
  • From: "Peter Pein" <petsie at>
  • Date: Wed, 29 Sep 2004 03:15:30 -0400 (EDT)
  • References: <cjaru4$nni$>
  • Sender: owner-wri-mathgroup at

"Narasimham G.L." <mathma18 at> schrieb im Newsbeitrag
news:cjaru4$nni$1 at
> There is error in si[t] even after the interpolating function is
> obtained. Thanks for fix.
> NDSolve[  {si2'[t] == 2, si2[0] == 0,
> th2'[t] == Sin[si2[t]]/r2[t], th2[0] == 0, r2'[t] == Cos[si2[t]],
> r2[0] == 1}, {si2, r2, th2}, {t, 0, 25}]; r [t_] = r2[t] /. First[%];
> th[t_] = th2[t] /. First[%];
> (* error -> *)  si[t_] = si2[t] /. First[%];

Did you have a look at si2'[t] == 2, si2[0] == 0 ?

But in general I would suppose to do sth. like:


or if I were a busy guy:


Since % gives the last result generated, the assignment of th went wrong
because the last generated result was InterpolatingFunction[{0.,25.},"some
table"]. So you asked Mathematica to do
which is correct in syntax but gives no sense (at least to me).

Peter Pein, Berlin
to write to me, start the subject with [

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