Re: Eureqa - Simplification done by Eureqa

[Alison Reynolds]

Hi Rick,

There is an option to disable automatic simplification if you go to Tools > Options > Solutions.  Try deselecting the simplification options.  You may have to run the search again briefly to get the solutions displayed in the new format.  Here's what I got by doing this in the project you sent:

y = -6.08 + 6.08*((1 - exp((-x)/126.6))/(x/126.6)) + 6.83*((1 - exp((-x)/126.6))/(x/126.6) - exp((-x)/126.6)) + -0.02012*((1 - exp((-x)/2.81))/(x/2.81) - exp((-x)/2.81))

Hope that helps,

Alison

On Sat, Jul 20, 2013 at 7:51 PM, Rick Steinert <rickst...@googlemail.com> wrote:

Dear reader,

I have to estimate the constants f0 to f5 of the following equation:

y = f0() + f1()*((1 - exp((-x)/f2()))/(x/f2())) + f3()*((1 - exp((-x)/f2()))/(x/f2()) - exp((-x)/f2())) + f4()*((1 - exp((-x)/f5()))/(x/f5()) - exp((-x)/f5()))

After hours of calculating, Eureqa provides the solution

y = 0.0201162113209185*exp(0.355872658309908*(-x)) + (1633.68739085227 + 0.0565264311578569*exp(0.355872658309908*(-x)) - 1633.74391728343*exp(0.00790201214436674*(-x)))/x - 6.07958467618524 - 6.82971046168988*exp(0.00790201214436674*(-x))

which fits the data quite well. Nevertheless, it is obivious that Eureqa simplified the equation quite much. Unfortunately, I tried hard in getting back to the factors I want to be estimated, but I cant. Can therefore someone tell me:

1) How to get back to the six factors I wanted to estimate by rearranging the formula (if there is no error of Eureqa present) or

2) How to extract the factors directly from the programme?

You can find the data of the project attached to this message.

Thanks in advance,

Rick

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