MATLAB Answers

display functions and coefficients from the basic fit tool box on a plot

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Jamie Williamson
Jamie Williamson on 15 Sep 2021
Commented: Chunru on 15 Sep 2021
Is there away to show basic fitting on a plot whenever the code is run? rather then going to tools > basic fitting and manually doing it everytime?? I want to show the function and coeffecients on a plot everytime the code is run and the plots are produced

Answers (2)

Chunru
Chunru on 15 Sep 2021
Edited: Chunru on 15 Sep 2021
Use your own fitting function:
% Some data
x = 0:.1:10;
y = x.^2 +2*x + 3 +randn(size(x))*.4;
plot(x, y)
% fitting (polyfit of order of 2)
p = polyfit(x, y, 2)
p = 1×3
1.0135 1.8552 3.2872
% Plot the fitting result
hold on
plot(x, polyval(p, x), 'r--')
  1 Comment
Jamie Williamson
Jamie Williamson on 15 Sep 2021
Iv got some data points and three fuctions I want to plot with a curve fit and also have the functions printed on the graphs. is this possible??
Data Functions
x y y = 0.6580x-1.337209
3.25 0.801369 y = 0.0632e^0.7817x
3.375 0.883622 y = 0.0379x^2.5890

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Chunru
Chunru on 15 Sep 2021
Edited: Chunru on 15 Sep 2021
xy = [3.25 0.801369;
3.375 0.883622];
x = xy(:, 1);
y = xy(:, 2);
f1 = @(x) 0.6580*x-1.337209;
f2 = @(x) 0.0632*exp(0.7817*x);
f3 = @(x) 0.0379*x.^2.5890;
f1str = char(f1);
f2str = char(f2);
f3str = char(f3);
plot(x, y, 'b');
hold on
fplot(f1, x([1 end])', 'g');
fplot(f2, x([1 end])', 'k');
fplot(f3, x([1 end])', 'r');
legend({'Data', f1str(5:end), f2str(5:end), f3str(5:end)}, 'Location', 'Best')

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