I am using tutorial frequency domain linear regression but I can't understand some parts.

tsdft = fft(ts-mean(ts));

freq = 0:1/72:1/2;

plot(freq.*12,abs(tsdft(1:length(ts)/2+1)),'o-', ...

'MarkerFaceColor','auto')

xlabel('Cycles/Year')

ylabel('Magnitude')

ax = gca;

ax.XTick = [1/6 1 2 3 4 5 6];

how you calculate freq?

why is multiply by 12?

In graph 1/6 used instead o??

kindly help me in regard

Waiting for your response

[Daniel M]

Hello! I suggest reading the two following pages, and following the examples.

https://www.mathworks.com/help/matlab/ref/fft.html

https://www.mathworks.com/help/matlab/math/using-fft.html