The Origin Forum
File Exchange
Try Origin for Free
The Origin Forum
Home | Profile | Register | Active Topics | Members | Search | FAQ | Send File to Tech support
Username:
 Password:
Save Password
Forgot your Password? | Admin Options

 All Forums
 Origin Forum
 Origin Forum
 4th-order polynomial fitting		  New Topic  Reply to Topic
 Printer Friendly
Author Previous Topic Topic Next Topic Lock Topic Edit Topic Delete Topic New Topic Reply to Topic

Farqhuit

United Kingdom
13 Posts
Posted - 01/24/2023 :  10:42:47 AM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Origin Ver. and Service Release (Select Help-->About Origin): Pro 2021b SR2 9.8.5.212
Operating System:Win 10

I have x and y data. When I do a polynomial fit, I get a reasonable fit from 4th-order. However, when I use the formula from the fit as a formula in the worksheet (col C) I get a rather different fit from my y data.

I tried parenthisizing the formula but it makes no difference.

When I apply the formula with a calculator it consistently returns the same result, that is, it matches the formula in the worksheet but not the 4th-order fit.

Can someone tell me what's going wrong? Thanks
https://my.originlab.com/ftp/forum_and_kbase/Images/4th%20order%20fit.opju

Farqhuit

snowli

USA
1420 Posts
Posted - 01/24/2023 :  11:07:25 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hello,

This is because we don't show full precision in FitPolynomial1.
E.g. if u right click Parameters table node and choose Digits... and change Decimal places to 10. U can see more digits.

U can right click Parameters table and choose Create Copy as New Sheet.
Then in the newly added parameters1 sheet, right click the cell to copy full precision.

Thanks, Snow
Go to Top of Page

Farqhuit

United Kingdom
13 Posts
Posted - 01/24/2023 :  11:31:53 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Thanks for that Snow, that's done the trick. The copy full precision is a handy trick, and I wasn't sure if the extra precision was available as it was not obvious how to access it.

Farqhuit
Go to Top of Page

snowli

USA
1420 Posts
Posted - 01/24/2023 :  12:12:10 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Sorry that I forgot to to mention FAQ related to this

https://www.originlab.com/doc/en/Quick-Help/Display-Calculate-Precision
https://www.originlab.com/doc/Quick-Help/AnalysisResult-Precision

And how to access result values in such hierachical tables in Set Column Values.
https://www.originlab.com/doc/Quick-Help/refer-to-fitting-parameters-in-SCV

Thanks, Snow
Go to Top of Page
  Previous Topic Topic Next Topic Lock Topic Edit Topic Delete Topic New Topic Reply to Topic
 New Topic  Reply to Topic
 Printer Friendly
Jump To:
The Origin Forum © 2020 Originlab Corporation Go To Top Of Page
Snitz Forums 2000