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[SOLVED] Derivatives of CombiTable output

#9963  Permalink Top

[SOLVED] Derivatives of CombiTable output

May-11-20 16:22:35

The derivative that any CombiTable is providing is far from being accurate.
Even by imposing a Continuous Derivative, the output is the following.

Any issue that I made?

Here the image (the OpenModelica Forum Attachment is broken)
https://ibb.co/HFXkj4w

Edited by: DarioMangoni - May-12-20 09:07:15
#9965  Permalink Top

Re: [SOLVED] Derivatives of CombiTable output

May-11-20 21:51:39

If the function goes from 0 to 1 in 0.25, the average derivative is 4. If the function is a sinus, the maximum derivative will be 2*pi, because the function displayed would be  y[1]=sin(2*pi*time), so the result seems not so bad.

#9969  Permalink Top

Re: [SOLVED] Derivatives of CombiTable output

May-12-20 09:06:46

Oh stupid me.
Really sorry.

I have been misleaded by the strange shape at the peak. However, it's just an artifact that comes from the quickly changing function that deceives the derivative evaluation.

Thanks a lot

#9971  Permalink Top

Re: [SOLVED] Derivatives of CombiTable output

May-12-20 09:52:53

Do not worry, this type of problems happen to all of us from time to time. At the beginnings I was also surprised by the result.

Regards

Carlos

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