MATLAB Answers

how to find the best curve fit for a set of data?

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Deva Narayanan
Deva Narayanan on 28 Dec 2018
Commented: Deva Narayanan on 29 Dec 2018
i have set of data points and want to know the best curve fit equation for this data . can any one explain me

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Image Analyst
Image Analyst on 28 Dec 2018
Do you want to include the flat parts in the fit?
Do you want a piecewise fit, like one for the flat parts and one for the curved parts?
Is there any particular model you'd like (exponential, polynomial, etc.)?
[data, strings, raw] = xlsread('matlab_data.xls')
x1 = data(:, 1);
y1 = data(:, 2);
x2 = data(:, 4);
y2 = data(:, 5);
subplot(2, 1, 1);
plot(x1, y1, 'b-', 'LineWidth', 2);
grid on;
subplot(2, 1, 2);
plot(x2, y2, 'b-', 'LineWidth', 2);
grid on;
0001 Screenshot.png
Deva Narayanan
Deva Narayanan on 29 Dec 2018
yes i need piecewise polynomials for both curved and flat model

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Answers (1)

KSSV
KSSV on 28 Dec 2018
[num,txt,raw] = xlsread('Matlab_data.xls') ;
x1 = num(:,1) ; y1 = num(:,2) ;
p = polyfit(x1,y1,3) ;
x1i = x1 ;
yi = polyval(p,x1i);
y1i = polyval(p,x1);
plot(x1,y1,'r')
hold on
plot(x1i,y1i,'b')

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