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TJ_107396118-Gravel
8-Gravel
Jul 17, 2023 8:30 PM UTC
Solved

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

 

 

Werner_E
Werner_EAnswer
25-Diamond I
Jul 17, 2023 9:21 PM UTC

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

 

 

 

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5 replies

terryhendicott
terryhendicott21-Topaz II
21-Topaz II
Jul 17, 2023 8:52 PM UTC

Hi,

Simply use better guesses with MPa not Pa

Capture.JPG

Prime 9 file only

Cheers

Terry

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    TJ_107396118-GravelAuthor
    8-Gravel
    Jul 18, 2023 12:05 PM UTC

    Terry, 

     

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

     

    All the best

     

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    Werner_E
    Werner_E25-Diamond IAnswer
    25-Diamond I
    Jul 17, 2023 9:21 PM UTC

    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

     

     

     

    Translate
      Werner_E
      Werner_E25-Diamond I
      25-Diamond I
      Jul 17, 2023 9:40 PM UTC

      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

       

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        TJ_107396118-GravelAuthor
        8-Gravel
        Jul 18, 2023 12:06 PM UTC

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

         

        All the best

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