| T O P I C R E V I E W |
| matsmcfly |
Posted - 01/11/2016 : 4:28:59 PM
Hi,
I am a regular user of Origin and have used several unique functions for fitting with in the past.
Today I have tried to fit a very simple function; however just can not get it to work. I have a data set to which I am trying to fit the function P = B * cos(x)^2
(NOTE: just to make clear that this is a cos squared term)
P is what I measure; B is a fixed parameter or constant to be evaluated by fitting; and x is what I measure.
Any pointers would be greatly appreciated.
Cheers,
Martin
Origin 2015, SR2. Running on Windows 10 64-bit |
| 2 L A T E S T R E P L I E S (Newest First) |
| Shirley_GZ |
Posted - 01/12/2016 : 01:49:14 AM
Hi Martin,
You need revise your fitting function as below:
P=A*cos((x-40)*pi/180)^2
As we know, cos(90°)=0. In you experiential data, when X=130, Y is close to 0. So you need add a X offset(about 40 here) on your fitting function. Then you need convert X values in degree to radians values by multiplying by pi/180.
You can see the fitting results I did:
Thanks,
Shirley
Originlab Technical Service Team |
| matsmcfly |
Posted - 01/11/2016 : 4:31:34 PM
Data set that I am trying to fit:
A(x) B(y)
50 0.43
70 0.35
90 0.20
110 0.07
130 0.005
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