Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2006
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2006

[Date Index] [Thread Index] [Author Index]

Search the Archive

RE: NDolve + ParametricPlot

  • To: mathgroup at smc.vnet.net
  • Subject: [mg67556] RE: [mg67513] NDolve + ParametricPlot
  • From: "David Park" <djmp at earthlink.net>
  • Date: Fri, 30 Jun 2006 04:15:19 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Paolo,

It is easier to actually define your x function.

Clear[x]
sol = NDSolve[{x''[t] == x[t], x[0] == 1, x'[0] == 1.1}, x, {t, 0, 3}];
x[t_] = x[t] /. First@sol
InterpolatingFunction[{{0., 3.}}, <>][t]

ParametricPlot[{x[t], x'[t]}, {t, 0, 3}];

Generally it is best to manipulate and define the expression you are going
to plot outside of any plot statement. For one thing you can see what you
are actually dealing. Then plug the final result into the plot statement.

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/


From: Paolo Pani [mailto:paolopani at RIMUOVEREgmail.com]
To: mathgroup at smc.vnet.net


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



  • Prev by Date: Re: Packages--Problem in evaluating functions from my own package!!!
  • Next by Date: Pasting a color from DrawGraphicsPalette
  • Previous by thread: Re: NDolve + ParametricPlot
  • Next by thread: Change Symbol in ListPlot