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MathGroup Archive 2007

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Re: optimizing

  • To: mathgroup at
  • Subject: [mg74902] Re: optimizing
  • From: dh <dh at>
  • Date: Tue, 10 Apr 2007 06:02:01 -0400 (EDT)
  • References: <evabpk$df6$>


your model function has the form: Exp[-k t], no need to solve an DE. Now 

you have the model function and your data and you can e.g. use "FindFit" 

to get the obtimal k.


kaiwan wrote:

> Hi! I have to find the best parameter "k" with witch function sd[k]->minimum. I do that with FindMinimum.  "sd" if a function that calculates the standard deviation from my experimental and model data. The model data is obtained from the mathematical model, first order differential equation...which I solve using NDsolve. The problem is that I cant make NDSolve work under FindMinimum. 


> Something like this:

> First, I define function that hace to solve the equation c'[t] == -k c[t], where "k" is a variable. This gives me model data later on. I define it as a function cause I dont know the value of "k" yet. 


> Then I define another function which calculates the standard deviation:

> sd[k_]:= function(model data, experimental data)


> Still I have no concrete results. 


> Then I use FindMiniumm for finding the "k" that gives the smallest Standard Deviation

> FindMinimum[sd[k], {k, 0.04}]


> And her is the problem, I cant make this combination to work .... help please? Many thanks!


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