Re: Plot artifact of NDSolve result

*To*: mathgroup at smc.vnet.net*Subject*: [mg116114] Re: Plot artifact of NDSolve result*From*: Oliver Ruebenkoenig <ruebenko at wolfram.com>*Date*: Wed, 2 Feb 2011 07:03:23 -0500 (EST)

On Wed, 2 Feb 2011, Bert RAM Aerts wrote: > Both in Mathematica 8.0.0 and 7.0.1 the plot of NDSolve result is > wrong near x-axis point 60. But when zooming in, plot is correct. > > Notebook and screenshot of result are available on http://users.skynet.be/fa991376/ > > eqn4 = y''[t] == -y[t]^2 + t > > sol4 = NDSolve[{eqn4, y[0] == 0, y'[0] == 1}, y, {t, 0, 70}, > WorkingPrecision -> 20, MaxStepSize -> 0.01] > > Below plot contains the artifact: > > Plot[Evaluate[{y[t], y'[t], y''[t]} /. sol4], {t, 0, 70}, > PlotRange -> All] > > Below plot is correct: > > Plot[Evaluate[{y[t], y'[t], y''[t]} /. sol4], {t, 50, 70}, > PlotRange -> All] > > Is there a way to avoid this? > > You could use Plot[Evaluate[{y[t], y'[t], y''[t]} /. sol4], {t, 0, 70}, PlotRange -> All, PlotPoints -> 30] Oliver