       RE: NDSolve help

• To: mathgroup at smc.vnet.net
• Subject: [mg43635] RE: [mg43626] NDSolve help
• From: "David Park" <djmp at earthlink.net>
• Date: Sat, 27 Sep 2003 04:57:55 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

```I had no trouble with your input in Version 5.0. I did remove the ";" at the
end to see the results, which are InterpolatingFunctions.

In Version 4.2.1, Mathematica stopped midway through the range due to
exceeding the maximum number of steps. (So that is certainly one thing that
is better in Version 5.)

Your equations appear to be proper so I don't understand why you are getting
initial conditions messages.

David Park

From: sashan [mailto:mabus at operamail.com]
To: mathgroup at smc.vnet.net

I'm a newb to mathematica. I'm trying to use NDSolve for a system of 2
2nd order ODE's and it complains that the number of initial conditions
(4) is not equal to the total order of the system (2). But I'm pretty
sure I've specified all the initial conditions. I've pasted the NDSolve
code I'm trying to write.

\!\(\(solution\  = \ NDSolve[{\(y''\)[t] == \(-\((\(-\ x[
t]^2\) + y[t]\ v^2)\)\), \ \(x''\)[
t] == \(-\((\ x[t] y[t] + x[t] v^2)\)\),
y == 0, \(y'\) == \(-1\), x[
0] == 1, \(x'\) == 0} /.
v -> \@\(\(x'\)[t]^2 + \(y'\)[t]^2\), {x, y}, {t, 0,
200}];\)\)

Thanks

```

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