Re: Plot artifact of NDSolve result
- To: mathgroup at smc.vnet.net
- Subject: [mg116141] Re: Plot artifact of NDSolve result
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Thu, 3 Feb 2011 05:30:35 -0500 (EST)
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];
Change (increase) the number of initial sample points (PlotPoints).
Plot[Evaluate[{y[t], y'[t], y''[t]} /. sol4], {t, 0, 70},
PlotRange -> All, ImageSize -> 400,
PlotPoints -> 25]
Bob Hanlon
---- Bert RAM Aerts <bert.ram.aerts at gmail.com> 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?