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Optimizing Integer Increment

Posted: Thu Dec 16, 2010 5:00 pm
by noorubm

I have a question about the optimizer tool in Multiple Run Fitter. I would like to vary one of the parameters as an integer. Please let me know if there is an way to do that.

Thank you in advance.


Re: Optimizing Integer Increment

Posted: Thu Dec 16, 2010 5:08 pm
by ted
That's not going to work with Praxis. In general terms, optimization means finding the particular combination of values for parameters a_0, a_1, . . . a_n-1 that minimizes the objective function f(a_0, a_1, . . . a_n-1). Praxis requires that each a is continuous over some interval. If you know that one of the parameters, say parameter a_n-1, can only have integer values, and you can furthermore stipulate that this parameter can have only one of m different values, then you could recast the problem like so:
Given a set of integer values i_0, i_1, . . . i_m-1, define functions g_k(), where k = 0, 1, . . . m-1, such that
g_k(a_0, a_1, . . . a_n-2) = f(a_0, a_1, . . . a_n-2, i_k)
Then you have m different subproblems: for each k, find the combination of values for a_0 . . . a_n-2 that minimizes g_k. The final step is to find which g_k has the smallest minimum.

Otherwise you could give up on Praxis and add another optimizer of your own choice.

Re: Optimizing Integer Increment

Posted: Sun Dec 19, 2010 12:33 am
by noorubm
thank you so much. I wrote a loop and it works fine.