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Genfit Guess Problem

TJ_10739611
8-Gravel

Genfit Guess Problem

Hi all,

 

I am trying to perform a 4 parameter logistic regression using genfit on a data set in Mathcad prime 4.0. I already have done this regression online, so I know what my guess values should be. I just want it for Mathcad workflow. Unfortunately, I am getting a real number error, even with close guess values. Is there any way to see the domain of these guesses? I hope this isn't a rendundant question to the site, and I've attached my document to look at.

 

Thanks a ton in advance!

(picture if needed)

TJ_10739611_0-1689625752513.png

 

 

ACCEPTED SOLUTION

Accepted Solutions
Werner_E
25-Diamond I
(To:TJ_10739611)

Your guesses for a and d are missing the factor 10^5

Werner_E_0-1689628785093.png

Werner_E_1-1689628817727.png

 

EDIT: Ooops, Terry was much faster 😉  Had not noticed Terry's reply until I posted mine.

 

EDIT2: Interestingly, NOT providing the vector F with the derivatives and just using the plain function f, seems to give an even slightly better fit

Werner_E_4-1689629368755.png

 

 

 

View solution in original post

5 REPLIES 5

Hi,

Simply use better guesses with MPa not Pa

Capture.JPG

Prime 9 file only

Cheers

Terry

Terry, 

 

Thank you so much! That's a quick and easy fix.

 

All the best

 

Werner_E
25-Diamond I
(To:TJ_10739611)

Your guesses for a and d are missing the factor 10^5

Werner_E_0-1689628785093.png

Werner_E_1-1689628817727.png

 

EDIT: Ooops, Terry was much faster 😉  Had not noticed Terry's reply until I posted mine.

 

EDIT2: Interestingly, NOT providing the vector F with the derivatives and just using the plain function f, seems to give an even slightly better fit

Werner_E_4-1689629368755.png

 

 

 

Werner_E
25-Diamond I
(To:Werner_E)

Just an additional remark. You may also use a solve block with minerr to get your parameters. Usually its less sensible wrt the guess values, but using your initial guesses it does not fails but returns useless results.
Given good guesses the result is pretty good, too:

Werner_E_5-1689630006681.png

 

Thank you so much!! That is so very helpful!!

 

All the best

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