Help me. How to plot sqrt(0.5 + 0.5 cos(w))

Help me. How can I plot sqrt(0.5 + 0.5 cos(w))

Sampling frequency at 8000 Hz

close all,clear all

f = 0:4000;
w = 2*pi*f;
x = 0.5+(0.5*cos(w));
M = sqrt(x);

figure(1)
subplot(211),plot(M),grid
xlabel('\omega/\pi'),ylabel('Magnitude'),title('Magnitude Spectrum')

Answer 1

[Birdman]

f = 0:0.1:40;
w = f;
x = 0.5+(0.5*cos(w));
M = sqrt(x);
semilogx(w,M),grid on
xlabel('\omega/\pi'),ylabel('Magnitude'),title('Magnitude Spectrum')

Try this code. Note that for magnitude plots, you have to use semilogx.

[Pruch Sawetratanastien]

Thank you, I'll try your code

Answer 2

[KL]

Sampling frequency is the interval with which you sample

 fs = 8000;

Now you use this to generate the 't' vector

 t = 0:(1/fs):5;

then you calculate 'w'

 w = 2*pi*t;

then you calculate your wave

 y = sqrt(0.5+0.5*cos(w));

Now you plot y against t,

 figure(1)
 plot(t,y)
 xlabel('\omega/\pi'),ylabel('Magnitude'),title('Magnitude Spectrum')

[Pruch Sawetratanastien]

Excuse me, why t = 0:(1/fs):5;

[KL]

when they tell you sampling frequency is 8000Hz, it means you are sampling the wave at 1/8000 second. That's why 1/fs. It is like the step size, read the following link

https://de.mathworks.com/help/signal/ug/changing-signal-sample-rate.html

So when you write

 0:(1/fs):5

it means you're creating a time vector from 0 to 5 seconds with a step size of 1/8000 second. You use 't' then to calculate 'w' and then the wave itself.

[Pruch Sawetratanastien]

Thank you!