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Topic: BUG: Evaluate/Trace of a Function

Dear Ivan

Good morning;

I have been frequently faced a bug during using "Evaluating or Trace a Function" tools in high order polynomial curve fitting.

for example referring to attached Graph file, i put a set of point and fitted a 6th order polynomial. When i active Evaluate function tool and trace points, the slope of curve after x=46 grow up (in against of curve shape). Even in x~90 we expect f'(x)=0 but in Graph we see -53!!

Please guide me about this discrepancy.

Thanks so much

Re: BUG: Evaluate/Trace of a Function

I think you forgot to attach the gif file.

Re: BUG: Evaluate/Trace of a Function

Excuse me. I attached a Graph file with a picture that shows error of f'(x) around mentioned range.

Post's attachments

Attachment icon Bug(Tangant)2.grf 6.1 kb, 1987 downloads since 2016-08-23 

Attachment icon bug.PNG 42.89 kb, 362 downloads since 2016-08-23 

Re: BUG: Evaluate/Trace of a Function

I have located the cause of the problem and I am trying to fix it. Thanks for notifying me about this problem.

Re: BUG: Evaluate/Trace of a Function

I have fixed the problem in the latest beta version:
http://www.padowan.dk/beta/

The cause of the problem was that Graph decided that the first part of the function, 9.43137423E-09, was so small that it could be rounded to zero. This optimization was a little too agresive.

Re: BUG: Evaluate/Trace of a Function

Thank you for your helpful assiduity.
Best regards