Re: NDSolve, Do loop, and Plot

*To*: mathgroup at smc.vnet.net*Subject*: [mg77308] Re: [mg77160] NDSolve, Do loop, and Plot*From*: DrMajorBob <drmajorbob at bigfoot.com>*Date*: Wed, 6 Jun 2007 07:26:23 -0400 (EDT)*References*: <5670411.1181046423565.JavaMail.root@m35>*Reply-to*: drmajorbob at bigfoot.com

I suppose you're using version 6? If so, Print solves the problem: ClearAll["Global`*"]; $TextStyle = {FontFamily -> "Arial", FontSize -> 12, FontSlant -> "Italic"}; Do[mysol[w] = NDSolve[{x'[t] == -y[t] - x[t]^2, y'[t] == w x[t] - y[t]^3, x[0] == y[0] == 1}, {x, y}, {t, 20}]; Print@Plot[{Evaluate[x[t] /. mysol[w]], Evaluate[y[t] /. mysol[w]]}, {t, 0, 20}], {w, 2, 4}] But I'd probably do it more like this: Clear[mysol] mysol[w_?NumericQ] := Module[{x, y}, NDSolve[{x'[t] == -y[t] - x[t]^2, y'[t] == w x[t] - y[t]^3, x[0] == y[0] == 1}, {x, y}, {t, 20}][[1, All, -1]]]; Block[{$TextStyle = {FontFamily -> "Arial", FontSize -> 12, FontSlant -> "Italic"}}, GraphicsColumn@ Table[{x, y} = mysol[w]; Plot[{x[t], y[t]}, {t, 0, 20}], {w, 2, 4}]= ] Bobby On Tue, 05 Jun 2007 05:34:48 -0500, DBK <boydkramer at gmail.com> 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}] > > > -- = DrMajorBob at bigfoot.com