How to find polynomial coefficient
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Giancarlo Mariani
am 27 Dez. 2017
Beantwortet: Sudheer Nuggehalli
am 2 Jan. 2018
Hello,
I've a set of data x and y that give a curve and I wanna find an approximation of this curve using the form y=a1*x+a3*x^3. Using the function polyfit I can obtain a cubic form y=a0+a1*x+a2*x^2+a3*x^3, but I need a0 and a2 equal to 0. How can i do?
Thank you in advance.
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Sudheer Nuggehalli
am 2 Jan. 2018
One possible way to go about doing this is to use the "fit" function, which creates the fit to the data in x and y with any custom model. The following code can be used as a starting point:
ft = fittype( @(a1,a3,x) a1*x+a3*x.^3 )
f = fit(x,y,ft)
The "fit" function requires an input argument object of type "fittype", which is created using the "fittype" function. The documentation pages below explain in greater detail how to use the "fit" and "fittype" functions, as well as detailed examples:
I hope this helps!
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