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
 User fitting function		  New Topic  Reply to Topic
 Printer Friendly
Author Previous Topic Topic Next Topic Lock Topic Edit Topic Delete Topic New Topic Reply to Topic

dominik.mierzwa

Poland
118 Posts
Posted - 03/29/2017 :  1:14:30 PM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Origin Ver. 2017 94E
Operating System: Windows 10 64bit

Hi,

I'd like to add user fitting function described with expression:

y=exp(-k*x^n)

where:

k and n are constants which should be calculated from the fitting

Starting conditions are as follows:
y0=1 - is moisture ratio from 1 to 0
x0=0 - is time from 0 to 21600 sec

Should k0 and n0 be also provided?
I have tried various combination with fitting function builder but unsuccessfully so far. How should I define such a function?



Kind regards,
Dominik

JacquelineHe

287 Posts
Posted - 03/30/2017 :  02:06:53 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi Dominik,

1.You can create the User-defined function in the Fitting Function Builder
To know more detail, please refer to this tutorial:
http://www.originlab.com/doc/Tutorials/UserDef-FitFunc

2. If you want to define the X and Y range used when you fit the dataset, you can custom the range in "Data Selection" page under "Setting" tab of the NLFit dialog
http://www.originlab.com/doc/Origin-Help/NLFit-Dialog-SettingsTab#Data_Selection

3. If "k" and "n" are the paramters in your function, the k0 and n0 are their "Initial Value", right?
If so you can custom them when you create this function (Fitting Function Builder dialog:Function Body Page:Parameters Tab) http://www.originlab.com/doc/Origin-Help/FitFuncBuilder-FuncBody ,
or custom them when you do fitting (NLFit dialog:Parameters Tab) http://www.originlab.com/doc/Origin-Help/NLFit-Dialog-ParaTab


Thanks
Jacqueline
OriginLab
Go to Top of Page

Marboulin

Canada
1 Posts
Posted - 04/03/2017 :  11:10:00 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi,

I was working before on Origin 7.0 and now we changed for 8.5. And in the 8.5 version the feature 'Fit Comparison' has disappeared... I was using that to compare the statistical differences between two Boltzmann fit (F-Test).
Can I still do Fit comparison in the 8.5 version? (don't want to compare dataset or models)

Thanks for your help!
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