how to set custom formula
• I want to eureqa search particular form of model . I have two input in following form

Z= a*X-b /(1-c*Y) . where, Z is output, X,Y are input and a,b,c are constants. I want eurequa  search this form of equation by optimizing a, b,c .
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• Hi pkp,

You'll want to edit the target expression in order to optimize coefficients for a known equation: http://formulize.nutonian.com/documentation/eureqa/user-guide/set-target/#target-expression (see section on fitting coefficients).

In your case, the target expression should look something like the following:
Z = f1()*X - f2()/(1-f3()*Y)

Thanks,
Jess
• Hi, new to Eureqa which I plan to use for scientific research. I would like to use eureqa to perform multiple Gaussian fits on an extended spectrum. One fit is given as y=f1()*exp(-1*(x-f2())^2/f3())) in which f1() gives me the amplitude of one Gaussian, f2() the centroid and f3() the 2 sigma-squared value. So far so good.
I presume that I cannot create own building blocks, so that I have to introduce a lot of functions for a spectra that e.g. contains 100 gaussian peaks distributed over 4096 to 8192 channels. Am I right?
Secondly, I would like to know whether it is possible to restrict the values in any of the functions? Most importantly I know (from the resolution of my detectors from which I am obtaining the spectra) that f3() will be between a maxima and minimum value e.g. in channels between 5 and 20. I have not yet figured out whether one can restrict a constant or how to do it in practise.
Any help will be welcomed, as I am intending to use Eureqa for some forthcoming publications.
Cheers, Klaus Spohr, Glasgow
• Hi Klaus,

Thanks for trying out Eureqa!

You might be interested in the "gauss(x) = exp(-x^2)" building-block. To constrain a coefficient to be positive you can change "y = f0()*x" ---> "y = abs(f0())*x" for example. For more complex constraints, you can use require(x) like "y = f0()*x + require(f0()>5) + require(f0()<10)" to require f0 to be between 5 and 10.

Best,
Jess

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