PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

DTFT, DFT, ZT, and FFT 545

0 10 20 30 40 50

0

5

10

15

20

abs[fft(gf(n))]

abs[fft(gf(n))] versus k

0 10 20 30 40 50

− 4

− 2

0

2

4

angle[fft(gf(n))] versus k

angle[fft(gf(n))]

0 10 20 30 40 50

0

5

10

15

20

abs[fft(gc(n))] versus k

index k

abs[fft(gc(n))]

0 10 20 30 40 50

− 4

− 3

− 2

− 1

0

angle[fft(gc(n))] versus k

index k

angle[fft(gc(n))]

FIGURE 5.58

Magnitude and phase plots of fft[gf (n)] and fft[gc(n)], over the range 1 ≤ k ≤ 50 of Example 5.13.

0 5 10 15 20 25 30 35 40 45 50

−0.5

0

0.5

error plots in time and frequency

Amplitude

− (^1005101520253035404550)
− 10
10
0
Magnitude error
0 5 10 15 20 25 30 35 40 45 50
0
10
phase error
index k
index n
error = g(n) - g(n)
∠error(k) = ∠DFT[gf(n)] - ∠DFT[gf(n)]
error = DFT[g(n) - DFT[g(n)]
FIGURE 5.59
Error plots in the time and frequency domains of Example 5.13.