Revising Levenberg Marquardt Method

Revising Levenberg Marquardt Method - Revising the Levenberg Marquardt Method with finite differences - Messages

#21 Posted: 1/21/2020 11:22:35 AM
Jean Giraud

Jean Giraud

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Carlos, my dear friend,
SS 6179 has found his Waterloo from your latest LM algo style,
but works fine from your original [2018] piece wise.
Seemingly the matter is some numerical issue,
but couldn't doctor that poisoned patient.
You know: can't doctor a stone ... too dead for too long !
No more worry, all the fits in my collection are done.
Still, LM is interesting.
Cheers ... Jean, take care and always be good.

Unsolved LM SS 6179.sm (134 KiB) downloaded 72 time(s).
#22 Posted: 1/22/2020 12:09:44 AM
CBG

CBG

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Dear friend Jean.
The problem in the calculation of the second LM algorithm in SS6179
occurs in the calculation of the Jacobian matrix for finite differences,
since in this step, after several iterations, for over unknown reasons an
overflow error occurs (possibly a calculation engine error ).
I have slightly modified the LMSA function and I have been able to solve the
problem indicated with 4 data. The solution that uses all the data is not possible in SS6179.

Solve_LMSA_SS6179.png

Solved LM SS 6179.sm (147 KiB) downloaded 73 time(s).


I hope you feel comfortable with this.


Best Regards

Carlos
1 users liked this post
frapuano 1/22/2020 12:46:00 PM
#23 Posted: 1/22/2020 12:23:25 PM
Jean Giraud

Jean Giraud

983 likes in 6866 posts.

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Wrote

I hope you feel comfortable with this.


Thanks Carlos for doctoring LMSA SS 6179.
You are right: some numerical issues between versions.
That was most noticed between the two SS 5346 Official
and SS 5346 UNofficial ... this version cured all "Official"
Included in the next Compendium Genfit Classroom Essentials
Cheers ... Jean

Genfit_11 Pharmacokinetics LMSA ... LM.sm (76 KiB) downloaded 56 time(s).
#24 Posted: 1/23/2020 1:31:42 PM
Jean Giraud

Jean Giraud

983 likes in 6866 posts.

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Hola, Carlos.
These two reconciliations [piecewise/global] work fine.
Will test more on hard fit.
Cheers ... Jean ... Thanks

Genfit_11 Pharmacokinetics LMSA ... [Carlos 2020].sm (50 KiB) downloaded 80 time(s).
Genfit_12 Pharmacokinetics LM ... [Carlos 2018].sm (43 KiB) downloaded 72 time(s).
#25 Posted: 1/24/2020 5:29:39 PM
CBG

CBG

77 likes in 312 posts.

Group: User

Wrote

Hola, Carlos.
These two reconciliations [piecewise/global] work fine.
Will test more on hard fit.
Cheers ... Jean ... Thanks



Hola Jean.

Thank you

Excellent job, it was possible to put the rattle on the cat!
but maybe it's time to migrate to the next version of SS.

Best Regards

Carlos
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