How to curve fitting for array?

I have 2 arrays, i've plotted them, now i needed to curve fitting for them. I've checked this page: https://www.mathworks.com/help/curvefit/fit.html

But it wasn't helpful for me.

Here is my code:

U=[10 9.7 9.4 9.1 8.8 8.5 8.2 7.9 7.6 7.3 7.0 6.7 6.4 6.1 5.8 5.5 5.2 4.9 4.6 4.3 4.0];
y1=[0.7 0.75 .8 .85 .9 1.05 1.05 1.1 1.1 1.1 1.15 1.15 1.10 1.1 1.1 1.1 1.1 1.15 1.10 1.15 1.2;0.75 0.75 0.85 0.95 1 1 1.05 1.1 1.1 1.1 1.1 1.15 1.2 1.2 1.25 1.25 1.25 1.3 1.3 1.3 1.35;.7 .75 0.75 0.8 0.85 0.85 0.9 0.95 1 1 1 1 1.05 1.05 1.05 1.1 1.1 1.15 1.15 1.15 1.2];
y2=[1.2 1.3 1.35 1.4 1.4 1.45 1.5 1.55 1.55 1.6 1.6 1.67 1.67 1.75 1.75 1.8 1.9 1.9 2 2.05 2.1; 1.25 1.3 1.4 1.4 1.45 1.45 1.5 1.55 1.6 1.65 1.65 1.7 1.7 1.75 1.85 1.9 1.9 1.95 2 2.05 2.1;1.2 1.25 1.3 1.35 1.4 1.45 1.5 1.5 1.55 1.6 1.6 1.65 1.7 1.7 1.75 1.8 1.85 1.9 1.95 2 2.05];
M1=mean(y1);
M2=mean(y2);
h=6.625.*10.^(-34);
m=9.109.*10.^(-31);
e=1.602.*10.^(-19);
lambda=h./sqrt(2.*m.*e.*U.*1000);


hold on
ylim([0.7 2.1])
xlim([1.22e-11 2.0e-11])

plot(lambda,M1)
plot(lambda,M2)

Answer 1

[Soumya]

Hi @Ege Tunç,

To perform cur fitting for the arrays that you have provided, you can utilize the ‘fit’ function in MATLAB. The ‘fit’ function creates the fit to the data in x and y with the model specified by ‘fitType’. The ‘fitType’ can be a character vector, string scalar, string array, cell array of character vectors, anonymous function, or a ‘fittype’ object created by the ‘fittype’ function.

The following code snippets can be added to your script to perform the curve fitting:

• Transpose the data because the fitting functions require input data as column vectors:

x = lambda'; 
y1_mean = M1'; 
y2_mean = M2'; 

• Use the fit function to perform curve fitting by specifying the desired fitType, example: 'poly2':

fit_y1 = fit(x, y1_mean, 'poly2'); 
fit_y2 = fit(x, y2_mean, 'poly2'); 

• Plot both the data points and the fitted curve. The same procedure can be applied to y2:

plot(x, y1_mean, 'bo', 'DisplayName', 'y1 Data');
x_fit = linspace(min(x), max(x), 100)';
plot (x_fit, fit_y1(x_fit), 'r-', 'DisplayName', 'y1 Fit');

The following is the received output:

To know more about the ‘fit’ function, you can refer to the following documentation:

https://www.mathworks.com/help/curvefit/fit.html#bto2vuv-1-fitType

I hope this helps!