defining a fitting type

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Wout Laeremans
Wout Laeremans 2023-1-12
编辑： Torsten 2023-1-16
I have written a funcion called Even_fit.m and there are 5 coefficients that need to be found from the fit (a,b,c,d,f) and there is one variable N that I want to load from the workspace, which is already fixed before fitting. My question is how I can load this variable in the fit, since when I do:
ft_even = fittype("Even_fit(x,a,b,c,d,f,N)");
It will also take N as a fitting coefficient, which I do not want.
Thank you!

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Torsten
Torsten 2023-1-12
编辑：Torsten 2023-1-12
My guess is
fitType = @(x,a,b,c,d,f)Even_fit(x,a,b,c,d,f,N);
fit(x,y,fitType)
  2 个评论
Torsten
Torsten 2023-1-16
编辑：Torsten 2023-1-16
Ran in:
Put the vector of the independent variable to the end of the input list for your function "EvenFit":
x = linspace(0,1,10).';
y = 3*x.^2 + 0.1*rand(10,1);
n = 12;
fitType = @(a,b,c,x)Even_fit(x,a,b,c,n);
sol = fit(x,y,fitType)
Warning: Start point not provided, choosing random start point.
sol =
General model: sol(x) = Even_fit(x,a,b,c,n) Coefficients (with 95% confidence bounds): a = 2.803 (2.517, 3.09) b = 0.2072 (-0.09066, 0.505) c = 0.009327 (-0.05463, 0.07328)
plot(sol,x,y)
function yfit = Even_fit(x,a,b,c,n)
yfit = a*x.^2+b*x+c;
end

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更多回答（1 个）

Steven Lord
Steven Lord 2023-1-12
See the "Create Custom Nonlinear Models and Specify Problem Parameters and Independent Variables" and "Use Anonymous Functions to Work with Problem Parameters and Workspace Variables" examples on the fittype documentation page.

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