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