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07-03-2020 10:28 AM

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Hi @altenbach,

1. I tried to break the equation into muliple parts for z. Since my z range is -50 to 700. These are parts I have gets where 6th order polynomial fits.

-50 to 61

61 to 192

192 to 278

278 to 346

346 to 401

401 to 446

446 to 477

477 to 599

599 to 668

668 to 700

2. "test RI_2Dpolynomial-set2_break.vi" is used where small sets of data is taken to see in which regions it shows polynonimal fit. One at time. First I tried on dataset of -50 to 61 ,then ran VI again for next data set and so on. Max error allowed is +-0.0999.

3. Then I ran test on all available data-points for -50 to 61 range and saw the results. It shows a poly fit of 6th order. Need to check for rest of changes though.

4. Still is there any better method which you can suggest? It may not poly fit always, may be any other non-linear fit ?

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altenbach

Knight of NI

07-03-2020 11:32 AM

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Yes, x and y (2nd and 3rd column) also form a reasonable grid and can be fit. However the fit does not look that great and might need higher terms, at least in one of the dimension..Of course a 2D polynomial is just a generic model and you could of course implement any other theory and use nonlinear fitting instead.

07-08-2020 05:25 AM

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Hi Altenbach,

Can u suggest some way to it?

Or some direction where to proceed to it?

07-09-2020 06:33 AM

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