Re: NDSolve, Do loop, and Plot
- To: mathgroup at smc.vnet.net
- Subject: [mg77296] Re: NDSolve, Do loop, and Plot
- From: dh <dh at metrohm.ch>
- Date: Wed, 6 Jun 2007 07:20:08 -0400 (EDT)
- References: <f43ese$151$1@smc.vnet.net>
Hi,
here is your clean up code, assuming you have not version 6:
mysol[w_?NumericQ]:=
NDSolve[{x'[t]\[Equal]-y[t]-x[t]^2,y'[t]\[Equal]w x[t]-y[t]^3,
x[0]\[Equal]y[0]\[Equal]1},{x,y},{t,20}][[1]]
Do[Plot[Evaluate[{x[t],y[t]}/.mysol[w]],{t,0,20}],{w,2,4}]
hope this helps, Daniel
DBK wrote:
> This seems like it should be easy, but it is giving me problems. I am
> running some simulations and would like to simply substitute in a
> different parameter value (w below) for each run of the simulation. I
> would then like to separately plot each variable (x and y below) for
> each simulation run with a different value for w. My code is below.
> When run, I get no error messages but no plot as well. I've tried
> pulling the Plot function out of the Do Loop but had no luck.
>
> Also, related to this, is it possible to provide mathematica with
> specific values of w instead of a range of values? For example, say I
> want to evaluate the simulation at w=2,5, and 14 instead of 2,3,4 as
> below.
>
> ClearAll["Global`*"];
> $TextStyle = {FontFamily -> "Arial", FontSize -> 12,
> FontSlant -> "Italic"};
> Do[mysol[w] =
> NDSolve[{x'[t] == -y[t] - x[t]^2, y'[t] == w x[t] - y[t]^3,
> x[0] == y[0] == 1}, {x, y}, {t, 20}];
> Plot[{Evaluate[x[t] /. mysol[w]], Evaluate[y[t] /. mysol[w]]}, {t, 0,
> 20}], {w, 2, 4}]
>
>