Re: Can't take a value from an InterpolatingFunction.
- To: mathgroup at smc.vnet.net
- Subject: [mg13638] Re: Can't take a value from an InterpolatingFunction.
- From: "Allan Hayes" <hay at haystack.demon.cc.uk>
- Date: Fri, 7 Aug 1998 09:14:05 +0100
- References: <6qbqv3$a71@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
John:
The following may be relevant
Table[First[y[100] /.
NDSolve[{x'[t] == y[t],
y'[t] == -0.01*y[t] - Sin[x[t]],
x[0] == 0, y[0] == y0}, {x, y}, {t, 0, 100},
MaxSteps -> 3000]], {y0, 2, 2.5, 0.1}]
{-0.594081,0.438559,1.46045,1.21722,0.449353,-0.834324}
Allan
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I. Ioannou wrote in message <6qbqv3$a71 at smc.vnet.net>...
>Hi all,
>
>I've set up and solved a system of two differential equations, according
>to the following prescription;
>
> solution =
> NDSolve[{r'[t] == .....equation1......,
> p'[t] == .....equation2......,
> r[0] == 0.,p[0] == p0}, {r, p}, {t, 0, 0.2},
> MaxSteps \[Rule] 300000, Method \[Rule] Automatic]
>
>All has worked very nicely. However, I need now to take the value of r
>at t=0.2 and I can't seem to be able to do it.
>
>I should point out that the Book suggestion r[0.2] /. % doesn't work,
>because the above statement is within a For loop and is run many times.
>(to collect various r[0.2] values that come out) So, it's within one
>big cell.
>
>The error reported sais that solution is not a valid lookup table. Well,
>from what I understand, it's a set (?) of two InterpolatingFunctions.
>If I knew what kind of entity solution is, I might be able to figure
>how to instruct Mathematica to let me access r[0.2].
>
>Any help appreciated, thanks, John
>
>--
> Ioannis I Ioannou phone: (206)-543-1372
> g-2 group, Atomic Physics fax: (206)-685-0635
> Department of Physics
> University of Washington e-mail: iioannou at u.washington.edu
>