Re: Re: Error with NDSolve

• To: mathgroup at smc.vnet.net
• Subject: [mg51010] Re: [mg50976] Re: Error with NDSolve
• From: DrBob <drbob at bigfoot.com>
• Date: Fri, 1 Oct 2004 04:49:13 -0400 (EDT)
• References: <200409280458.AAA23991@smc.vnet.net> <cjdq6g\$ass\$1@smc.vnet.net> <200409300852.EAA26524@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```All three schemes work just fine. If the first doesn't work for you, there's something wrong with your Mathematica installation or option settings.

Bobby

On Thu, 30 Sep 2004 04:52:30 -0400 (EDT), Narasimham G.L. <mathma18 at hotmail.com> wrote:

> DrBob <drbob at bigfoot.com> wrote in message news:<cjdq6g\$ass\$1 at smc.vnet.net>...
>> 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[%%]
>> si[t_] = si2[t] /. First[%%%]
>
> Above three lines have some problem,but next two schemes work fine, Thanks.
>
>> solution = First@
>>      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] /. solution
>> th[t_] = th2[t] /. solution
>> si[t_] = si2[t] /. solution
>
>
>> or (better yet):
>>
>> {r, th, si} = {si2, r2, th2} /. First@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}]
>>
>> Bobby
>>
>
>
>
>

--
DrBob at bigfoot.com
www.eclecticdreams.net

```

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