MATLAB: Polyfit: How to use

polyfitscatterplot

Dear MatLab community!
I'd like to lay a line of best fit in my scatterplot.
I did the following: 
figure;scatter(stimsAt10Hz_outdet(:,1),AQS(:,2), 40, [0.2 0.35 1], 'filled')
grid on
xlabel('Magnitude(z)')
ylabel('ASQ-Score')
title('Corr(Contour,ASQ)')
polyfit(stimsAt10Hz_outdet, AQS,1)
But nothing happens.
Do anyone find the error? I am not sure if I used polyfit in the right way..
I would be really thankful to hear something from you.
Thank you in advance!

Best Answer

I recommend using the examples in the documentation to guide you.
Here, you must use the exact same x and y values that you used in your plot command: stimsAt10Hz_outdet(:,1),AQS(:,2). You are passing in more. Polyfit does not know how to handle the extra data.
Polyfit also only returns the coefficients. Use polyval to calculate your fit's y values from a provided x vector. Then use hold on and plot commands to add your fit lines to your figure. See this example.
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