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DSolve to solve simultaneous ODEs

  • To: mathgroup at smc.vnet.net
  • Subject: [mg9443] DSolve to solve simultaneous ODEs
  • From: "Kelvin Yip" <ykelvin at unixg.ubc.ca>
  • Date: Wed, 5 Nov 1997 01:57:00 -0500
  • Organization: The University of British Columbia
  • Sender: owner-wri-mathgroup at wolfram.com

Hi Everyone,

Although I follow closely the Mathematica book's instruction , I still
only receive a out put which is just a parapharse of my input. The
Program (Version 2.2) work well on solving single equation but not a
systems of ODEs, anyone can help ?


DSolve[(u*x[t]*(1-x[t]/xmax)-x'[t]==0),x[t],t]
              t u
             E
{{x[t] -> -----------}, {x[t] -> 0}}
           t u
          E
          ---- + C[1]
          xmax

This one is OK but not the one below!


DSolve[{(u*x[t]*(1-x[t]/m)-x'[t]==0),
(n*x[t]-p'[t]==0),(-p'[t]/Yp-x'[t]/Yx-s'[t]==0)},{x,p,s},t]
                    x[t]
DSolve[{u x[t] (1 - ----) - x'[t] == 0, n x[t] - p'[t] == 0,
                     m

    p'[t]            x'[t]
  -(-----) - s'[t] - ----- == 0}, {x, p, s}, t]
     Yp               Yx


I have tried to load the DSolve package first then type my equation in,
still no success.

Thank you for your attention!

Kelvin Yip



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