Polyfit: How to use?

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!

Answer 1

[Cris LaPierre]

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.