How to find a figure of polynomial curve fitting for 3 matrices

Question

Elinbesti 2021-1-14

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https://ww2.mathworks.cn/matlabcentral/answers/717208-how-to-find-a-figure-of-polynomial-curve-fitting-for-3-matrices

回答： Dev 2025-8-26

Hello,

I have 3 matrices(mat1, mat2, mat3) and i found their averages one by one, and now i want to find their best polynomial curve fitting for each matrix(for each matrix should have 1 figrue of its polynomial curve fitting) by using X, average of (mat1, mat2 and mat3) and X2(X2 can be changable to suit for the best curve) as written in the codes bellow.

I'm able to do for 1 matrix but need help to do for 3 matrices

Many thanks in advance

clc

clear

X = [1 2 3];

mat1= [7 12 177;

0 10 7;

12 0 55];

mat2= [3 6 21;

0 4 3;

6 0 8];

mat3= [2 4 61;

0 3 2;

4 0 19];

Y = mean(mat1)

Y1 = mean(mat2)

Y2 = mean(mat3)

coefs = polyfit(X,Y,4);

X2= 1:0.1:3;

curve = polyval(coefs,X2);

plot(X2, curve, X, Y);

xlabel('x axis');

ylabel('y axis');

title('x and y');

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Answer 1

Dev 2025-8-26

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Hi @Elinbesti,

To plot the best polynomial curve for each matrix, we can modify the code provided in the question to use 2nd degree polynomials instead of 4th degree. Since we only have 3 data points, making 2nd degree more appropriate. Please find the updated code snippet below-

coefs = polyfit(X, Y1, 2); % Using 2nd degree polynomial

We can then use the “subplot” function along with the “figure” function to split our plots accordingly and plot all the three curves simultaneously.

I have attached an example figure after plotting all the three functions for your reference-