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 user defined nonlinear fitting model		  New Topic  Reply to Topic
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wz1416scripps

USA
24 Posts
Posted - 07/16/2015 :  5:55:08 PM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Origin Ver. and Service Release (Select Help-->About Origin): originpro 2015
Operating System:Win 7

Hi,

I am now defining a model for Originpro to fit my data.

The model is y=a*((3/2)*(x/b)-(1/2)*((x/b)^3)), if 0<x<=b
y=Max value, if x>b

I have already inputted the model y=a*((3/2)*(x/b)-(1/2)*((x/b)^3))(this is spherical model). However, I don't know how to add the additional constrain, such as if 0<x<=b, and y does not change (maintained as the max value) if x>b.

Can you help me? Thanks,
Chao.
Edited by - wz1416scripps on 07/16/2015 5:59:24 PM

jasonzhao

China
262 Posts
Posted - 07/16/2015 :  11:01:48 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hello,

Please refer to this tutorial, which introduce the fitting of Piecewise function;

http://www.originlab.com/doc/Tutorials/Fitting-Piecewise-Linear

You could try the function body like this:

if( x < b )
      y = a*((3/2)*(x/b)-(1/2)*((x/b)^3));
else
      y=a;



Best regards!
Jason
OriginLab Technical Service
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wz1416scripps

USA
24 Posts
Posted - 07/17/2015 :  01:15:32 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Thanks.
It works!

quote:
Originally posted by jasonzhao

Hello,

Please refer to this tutorial, which introduce the fitting of Piecewise function;

http://www.originlab.com/doc/Tutorials/Fitting-Piecewise-Linear

You could try the function body like this:

if( x < b )
      y = a*((3/2)*(x/b)-(1/2)*((x/b)^3));
else
      y=a;



Best regards!
Jason
OriginLab Technical Service
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