MATLAB: I want to add a line of best fit to the plot using the polyfit function.

bestfit

%Plot graph 1

figure(2); clf

plot(xL(A),anglex,'ko');

Best Answer

You can do something like this

p = polyfit(xL(A),anglex,1);
anglexFit = polyval(p,xL(A));
plot(xL(A),anglex,'ko',xL(A),anglexFit)

I'm assuming your variable A, is a vector of indices that give the elements of xL that you want plotted and fit.

Also you can enter the command doc polyfit on the command line and it will bring up the documentation for polyfit, which has some nice examples of plotting best fit lines.

Related Solutions

MATLAB: How to add line of best fit to plot

You are not accepting the coefficients from polyfit() - they basically are thrown away. Even if you did do

coefficients = polyfit(climb, calories, 2);

you still need to compute the fitted values, like

numFitPoints = 1000; % Enough to make the plot look continuous.
xFit = linspace(min(climb), max(climb), numFitPoints);
yFit = polyval(coefficients, xFit);
hold on;
plot(xFit, yFit, 'r-', 'LineWidth', 2);
grid on;

See attached demo, which produces the plot below.

MATLAB: Plot a straight line on another graph

It looks as though you want to plot tangent lines at specific points on the curve. See How to draw tangent line at infleciton point? for an example.

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MATLAB: How to add line of best fit to plot

MATLAB: Plot a straight line on another graph

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