I would like to know how can I plot amplitude and phase

I would like to know how can I plot amplitude and phase for (x=sin (t)+sin(t).*cos(t) ; for t=[0:0.07:20]

is this correct? or it needs correction?

t=[1:0.07:20];

x=sin(t)+sin(t).*cos(t);

y=fft(x,272);

y1=abs(y);

f=(100/7)/272*(1:272);

plot (f,y1(1:272))

title (‘ Frequency Domain’)

xlabel("f (Hz)")

ylabel("|y1(f)|")

y2=angle(y);

stem (f,y2)

Answer 1

[Star Strider]

I tweaked your code slightly.

Try this —

t=1:0.07:20; 
x=sin(t)+sin(t).*cos(t);
Fs = 1/0.07;                                        % Sampling Frequency
Fn = Fs/2;                                          % Nyquist Frequency
L = numel(t);
nfft = 2^nextpow2(L);                               % For Efficiency
y=fft(x,nfft)/L; 
y1=abs(y); 
f=(0:nfft/2)*Fn*2/nfft;

figure
plot (f,y1(1:numel(f))) 
title ('‘Frequency Domain’')  
xlabel("f (Hz)") 
ylabel("|y1(f)|") 
grid

y2=angle(y); 

figure
stem (f,y2(1:numel(f)))
grid

It could be interesting to see what the unwrap function does to the phase angle ‘y2’. I leave that experiment to you.

.