Hi,
I'm importing digitised graph data and wish to use a curve fit function. I have found only the Maxima 'Fit()' function, with reference to mkraska's file fit.sm (thank you mkraska).

https://en.smath.com/forum/yaf_postst7475_Curve-fit-function.aspx

I get an error when I open this file in my installation. I have installed maxima-5.45.1-win64.exe in a subdirectory in the Smath installation location.

Please see the error in the image attached.



Does this point to a known problem?

All help is much appreciated.

My file opens without error
Fit1.sm (15,26 KiB) scaricato 1270 volta(e).

I have shutdown and reopened and the Draw2d error has disappeared.
In mkraska's example, a result could be produced for L:=()= but mine can't "A - not defined", any ideas why this would be?

Ber7, thank you for checking for me, not sure why now ok.

Wrote

I'm importing digitized graph data and wish to use a curve fit function

1. Cholesky is the first classroom.
Rarely useful as very few physical phenomenons are poly type.
You can trick the exponents of the monomials.
2. Next is Padé rational fraction... needs lot more data points.
3. Else are model function [imagination is the limit].
That is a season Classroom !
The core component is Cholesky in Conjugate Gradient.

Jean,
Thank you for the illustration of Cholesky. My property curves are well behaved as in your example so I'm sure that this will be ok.
Much appreciated,
Tim

Wrote

I have shutdown and reopened and the Draw2d error has disappeared.
In mkraska's example, a result could be produced for L:=()= but mine can't "A - not defined", any ideas why this would be?

You have to switch to optimization none in the context menu. The result of Fit() is displayed as list of equations name=value. If you try to numerically evaluate this, then you get the error that A isn't defined.

Assign() converts the equations into assigments, so that further down the variables have numerical values.

Wrote

Jean,
Thank you for the illustration of Cholesky.
My property curves are well behaved as in your example so I'm sure that this will be ok.
Much appreciated,
Tim

Your data set is OK, compatible to poly 3.
More visit c/w error bar.
Thanks for your appreciation ... Cheers ... Jean

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