RE: Plotting direction fields for a logistic equation

*To*: mathgroup at smc.vnet.net*Subject*: [mg37217] RE: Plotting direction fields for a logistic equation*From*: "Annetts, Dave (E&M, North Ryde)" <David.Annetts at csiro.au>*Date*: Thu, 17 Oct 2002 00:08:39 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Hi Ruben, > 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 Just a thought, but have you checked your function for typos? As you've written it, f is only a function of y .... Regards, Dave.