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MathGroup Archive 2002

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Re: ORDINARY DIFFERENTIAL EQUATION

  • To: mathgroup at smc.vnet.net
  • Subject: [mg32182] Re: ORDINARY DIFFERENTIAL EQUATION
  • From: "Carl T. Bergstrom" <cbergst at nospam.u.washington.edu>
  • Date: Fri, 4 Jan 2002 05:03:58 -0500 (EST)
  • References: <a0ugmj$5t3$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

> I am trayin to plot the directin of vector field of system of ordinary
> differential equation but i could not
> 
> the system is
> x'[t]=(1-x[t]-0.5 y[t])x[t]
> y'[t]=(1-y[t]-0.8 x[t])y[t]
> 

How about 

  <<Graphics`PlotField`

  v[x_,y_]:={(1-x-0.5 y)x, (1-y-0.8 x)y}

  PlotVectorField[v[x,y], {x,0,1}, {y,0,1}, ScaleFactor->.25]	

Of course, you can make the picture a lot prettier using David Park's DrawGraphics
packages; see http://home.earthlink.net/~djmp/   if you want to take this
approach.


-----------------------
Carl T. Bergstrom                
Department of Zoology
University of Washington      
http://octavia.zoology.washington.edu            
-------------------------------------


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