Re: Possible bug?

[Doug Stewart]

On Fri, Feb 9, 2018 at 7:06 AM, mrodrig <address@hidden> wrote:

Hello,

I am trying to make a data fitting using the leasqr function. In the
attachment you can find the data and the function that I am trying to adjust
and the adjustment parameters.

When plotting x vs y and the F function with the par parameters, initially
it seems reasonable.

When I make the adjustment I get the following result

error: weighted residuals are not real
error: called from
     __lm_svd__ at line 467 column 11
 
I searched and there are other users that something similar has happened to
them

Somebody could help me

Data_fitting.txt
<http://octave.1599824.n4.nabble.com/file/t372706/Data_fitting.txt>



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I tried your code, and see the same error as you reported.

I don't know for sure what the problem is, but your equation is a way too long.

I would suggest starting with only 2 or 3 terms and git that much working, and then add more terms as is needed.

Usually one wants the shortest equation possible, unless you have some physics that says what the equation looks like.  

There is also some places in your equation that could be ambiguous, so add more brackets.

 

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DAS