How do I plot Magnitude And Phase Response of a DT Signal

So I have a DT Sequence of [-2 5 11 4] how do i plot its magnitude and phase response?

t = 1:100;
y = [-2 5 11 4]
subplot(2,1,1)
stem(abs(y)), title('Amplitude plot')
subplot(2,1,2)
stem(angle(y)), title('Phase plot')

Will this work? Just using abs and angle? or is the formula wrong? Do I need to DTFT first?

Answer 1

[Rick Rosson]

   doc fft