Why are the results calculated from the function "fmincon" not stable?

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kang wang
kang wang 2017-8-4
评论： Matt J 2017-8-4
Hallo everbody,
Recently I am doing the fit about burning velocity of fuels, which is one of the most important properties in the combustion field. The approximation formula is as follwed:
In this formular there are six coefficients, namely F,m,G,n,E,B. And the variables: p,Y,Tu,Tb are already given.
Then I use the mathematic function "fmincon" to calculate these six coefficients. I have set the initail coefficients value and the highst and lowest coefficients value. But the results calculated are not stable. The coefficients value are always changed.
I do not know where the problem is.
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Matt J
Matt J 2017-8-4
Are m and n supposed to be integers? FMINCON will not restrict its search to integers. You would need ga() for that.

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回答（1 个）

Anthony
Anthony 2017-8-4
to my understanding, all fmin*** functions are for local minimum only. If your function has multiple local minimizers, then the solution will depend on the initial condition.
  1 个评论
kang wang
kang wang 2017-8-4
Hello Anthony! First, thank you for your answer. In my case, the local minimizer is the least-square method as followed:
Futhermore, I used the "globalresearch" and "multistart" to run this script. And the results are still not stable.

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