Re: NDSolve, Do loop, and Plot

*To*: mathgroup at smc.vnet.net*Subject*: [mg77238] Re: NDSolve, Do loop, and Plot*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Wed, 6 Jun 2007 06:49:56 -0400 (EDT)*Organization*: Uni Leipzig*References*: <f43ese$151$1@smc.vnet.net>*Reply-to*: kuska at informatik.uni-leipzig.de

Hi, when you see nothing, than you are working with Mathematica 6.0 ?? Try mysol[w_?NumericQ] := 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]] Manipulate[ DynamicModule[{sol}, sol = mysol[w]; Plot[{x[t], y[t]} /. sol, {t, 0, 20}, Evaluated -> True]], {w, 2., 4}] Regards Jens 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}] > >