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TJ_107396118-Gravel
8-Gravel
July 17, 2023
Solved

Genfit Guess Problem

  • July 17, 2023
  • 2 replies
  • 2333 views

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

 

 

Best answer by Werner_E

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

 

 

 

2 replies

T
21-Topaz II
terryhendicott21-Topaz II
21-Topaz II
July 17, 2023

Hi,

Simply use better guesses with MPa not Pa

Capture.JPG

Prime 9 file only

Cheers

Terry

    T
    TJ_107396118-GravelAuthor
    8-Gravel
    July 18, 2023

    Terry, 

     

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

     

    All the best

     

    W
    Werner_E25-Diamond IAnswer
    25-Diamond I
    July 17, 2023

    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

     

     

     

      W
      Werner_E25-Diamond I
      25-Diamond I
      July 17, 2023

      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

       

        T
        TJ_107396118-GravelAuthor
        8-Gravel
        July 18, 2023

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

         

        All the best

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