Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2002
*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 2002

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

Search the Archive

RE: Plotting direction fields for a logistic equation

  • To: mathgroup at smc.vnet.net
  • Subject: [mg37220] RE: Plotting direction fields for a logistic equation
  • From: "David Park" <djmp at earthlink.net>
  • Date: Thu, 17 Oct 2002 00:08:46 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Ruben,

Your plot looks bad because PlotVectorField uses AspectRatio->Automatic,
which means that the t and y axes are at the same scale. This makes the plot
very high and narrow. Try the following...

PlotVectorField[f[t, y], {t, 0, 80}, {y, 0, 1400},
    AspectRatio -> 1,
    Frame -> True,
    ImageSize -> 450];

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

From: Ruben Garcia [mailto:rubgb at yahoo.com]
To: mathgroup at smc.vnet.net

Hi there:
I've been trying to use PlotVectorField for the
following differential equation:
dy/dt = 0.08*y*(1-y/1000)
but I haven't been successful yet.
I tried to do the following:
f[t_, y_] := {1, 0.08*y*(1 - y/1000)}
<<Graphics`PlotField`
PlotVectorField[f[t, y], {t, 0, 80}, {y, 0, 1400}];
but I'm getting a meaningless plot so I'd appreciate
if someone could tell me what is what I'm doing wrong.
Thank you very much in advance,
Ruben

__________________________________________________
Do you Yahoo!?
Faith Hill - Exclusive Performances, Videos & More
http://faith.yahoo.com



  • Prev by Date: Re: List processing
  • Next by Date: Re: c++ book
  • Previous by thread: Re: Plotting direction fields for a logistic equation
  • Next by thread: List processing