Custom equation error in fitting toolbox
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Hi, I'm trying to fit my data with a specific function trough the fitting tool. The equation that my datas should fit is 
, it's the distribution of a laser light interference when it pass trought one fenditure.
, it's the distribution of a laser light interference when it pass trought one fenditure.By the way the fitting tool cannot fit my data, the error reported is: "NaN computed by model function, fitting cannot continue.
Try using or tightening upper and lower bounds on coefficient". I think the problem is cause by 
because when I dont add to the box there's no error.
because when I dont add to the box there's no error. 2 个评论
Alex Sha
2021-12-10
Hi, post out your data if possible, it will be convenient for others to try your problem
Pietro Scapolo
2021-12-10
采纳的回答
Chunru
2021-12-10
The following function will result in undefined value for sin(x)=0
sin(a*sin(x))/(a*sin(x))
You can change this into sinc function (which take care of 0/0 case):
sinc(a*sin(x)/pi)
% which is equivalent to the first expression and eliminate the problem at
% sin(x)=0.
% doc sinc
3 个评论
Pietro Scapolo
2021-12-10
Chunru
2021-12-10
% The whole function should be
b*(sinc(a*sin(x)/pi)).^2
% the above is part of the function that cause the problem
Pietro Scapolo
2021-12-10
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