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MathGroup Archive 1996

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Nonlinear fit to diff eqs.

  • To: mathgroup at
  • Subject: [mg4973] Nonlinear fit to diff eqs.
  • From: mod <c530789 at>
  • Date: Thu, 17 Oct 1996 00:40:53 -0400
  • Sender: owner-wri-mathgroup at

Dear All,

My problem is to fit a set of data to a system of coupled first order
ordinary differential equations. The example is:

   Experimental data of y1, y2 and y3 as a function of time
             y1 = {a1,a2,a3,a4,.....,aN}
             y2 = {b1,b2,b3,b4,.....,bN}
             y3 = {c1,c2,c3,c4,.....,cN}
             time = {t1,t2,t3,t4,.....,tN}
    Equations to fit (for example):

             y1'[t] = k1 y1[t] + k2 (1-y1[t]-y2[t]) + k4 y3[t]
             y2'[t] = k2 y2[t] - k3 (1-y2[t]) + k4 y3[t]
             y3'[t] = k3 (1-y1[t]-y2[t]-y3[t]) +k2 y3[t] 

I need to fit my data to get those k1, k2, k3, and k4. What is the easiest
to to do this with Mathematica? Any package? Please help.

Thaks in advance,


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