| T O P I C R E V I E W |
| jh258 |
Posted - 01/27/2016 : 11:35:50 AM
Hi All,
I'm new to Origin and have a problem. I'm trying to curve fit some data but I need to use a sech function which is not built into Origin. How do I program/input this function so that I can use it in a similar manner to the built in ones?
Any help would be greatly appreciated.
Thanks,
Jeff
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| 1 L A T E S T R E P L I E S (Newest First) |
| SeanMao |
Posted - 01/28/2016 : 02:23:02 AM
Hi,
You can define an user fitting function on your own for sech.
Suppose the sech fitting function is as below:
sech(x,A,x_0) = 2*A/(exp(x-x_0)+exp(-x+x_0));
where sech(x) = 2/(exp(x)+exp(-x))
To do so, go to menu Tools: Fitting Function Builder to open dialog.
1. Click Next button.
2. Set Function Name as "sech". Click Next.
3. Input "A, x_0" in Parameters.
4. Click Next button. Input 2*A/(exp(x-x_0)+exp(-x+x_0)); in "y=0" edit box.
5. Click the running man button on the bottom middle to test formula is written correctly.
6. Click Finish button and the fitting function is created.
When you open Nonlinear fit dialog from menu Analysis: Fitting: Nonlinear Curve Fit, make sure in Function Selection page, select Category as "User Defined" and you will be able to select sech(User) from the Function dropdown list.
Regards!
Sean
OriginLab Tech.
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