Re: NDolve + ParametricPlot
- To: mathgroup at smc.vnet.net
- Subject: [mg67538] Re: [mg67513] NDolve + ParametricPlot
- From: Selwyn Hollis <sh2.7183 at earthlink.net>
- Date: Fri, 30 Jun 2006 04:14:13 -0400 (EDT)
- References: <200606290409.AAA29004@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Paolo, Look at the value of sol, and you will notice that NDSolve gives its result wrapped in an extra pair of braces. ParametricPlot doesn't like that. A simple fix is to put First@ in front of NDSolve, i.e., sol = First@NDSolve[{x''[t] == x[t], x[0] == 1, x'[0] == 1.1}, x, {t, 0,3}]; --- Selwyn Hollis On Jun 29, 2006, at 12:09 AM, Paolo Pani wrote: > Hi, i'm new with Mathematica..i'm getting mad with expressions like > this: > > sol = NDSolve[{x''[t] == x[t], x[0] == 1, x'[0] == 1.1}, x, {t, 0, > 3}]; > Plot[x[t] /. sol, {t, 0, 3}]; > Plot[D[x[t]] /. sol, {t, 0, 3}]; > ParametricPlot[Evaluate[{x[t] /. sol, D[x[t] /. sol]}], {t, 0, 3}]; > > The first two Plots are ok, the third give me: > > > > ParametricPlot::pptr: {InterpolatingFunction[{{0., 3.}}, {2, 2, True, > Real, \ > {3}, {0}}, {{\[LeftSkeleton]1\[RightSkeleton]}}, {{0, 3, 6, 9, 12, > 15, 18, \ > 21, 24, 27, \[LeftSkeleton]32\[RightSkeleton]}, {1., 1.1, \ > [LeftSkeleton]8\ > \[RightSkeleton], \[LeftSkeleton]113\[RightSkeleton]}}, {Automatic}] > [t]} > does \ > not evaluate to a pair of real numbers at t = 1.25`*^-7. > > > > > ... and "More..." does tell nothing more. > > Where is my mistake? > > Thanks and sorry for my bad english > > Paolo >
- References:
- NDolve + ParametricPlot
- From: Paolo Pani <paolopani@RIMUOVEREgmail.com>
- NDolve + ParametricPlot