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 Fitting driven harmonic oscillator function		  New Topic  Reply to Topic
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Tatrias

Spain
1 Posts
Posted - 11/09/2017 :  8:42:55 PM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Origin Ver.: OriginPro 8 SR0
Operating System: Win10

I have defined a custom fitting function to try to fit some data samples from a driven harmonic oscillator's frequency response. See this pastebin for the full function file: https://pastebin.com/Lucnitcz

More specifically, this is the function I'm trying to fit:


I'm not able to make this fitting converge. I don't have any readings for the force, the elastic constant or the oscillator's resonating frequency so I can't fix any parameters. Furthermore, my curve doesn't look at all like a frequency response of an oscillator if I set oscillator quality to anything different from 1. It looks like this:


Where did I go wrong? With quality 1, it does resemble a quality 1 response but fit still doesn't converge.

JacquelineHe

287 Posts
Posted - 11/10/2017 :  05:06:53 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi,

I am afraid I am not sure what leads the fitting can not converge just by the image.
Maybe the function is not suitable for your dataset. Maybe the initialize value of parameters are not suitable for your dataset. You can try to modify initialize value of parameters.

If you need us help for the modification the paramter value, I suggest you can send you project and the FDF file (Fitting Function file) that is saved in "User File Folder" by default. Then we can try to reproduce the question.

Tech Support department email: tech@originlab.com
Plesae note: please send us with your detailed version and Serial Number information? You can check it by selecting "Help: About Origin" in the menu.

Thanks
Jacqueline
OriginLab
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