如何用FFT來計算SNR及THD

TJ球

我用FFT軟體算出x=[1,2,3,4,5,4,3,2]8個序列點的值，

* [  C) w( b, C6 X; B8 ]X[0] = 24+(0)j
  Q$ U6 E( x: _3 v4 K/ oX[1] = -6.82842712475+(-1.33226762955E-15)j
9 f1 _/ I, x* R+ C) a3 ?! |X[2] = 3.09539720245E-17+(0)j
X[3] = -1.17157287525+(2.88657986403E-15)j
8 S4 {2 B, q6 [4 X, |X[4] = 0+(-4.89842541529E-16)j
5 `; h) k/ f2 h" NX[5] = -1.17157287525+(-2.44249065418E-15)j
X[6] = -9.86282453277E-15+(-6.66133814775E-16)j
! \( O- ]. Y7 a1 S, NX[7] = -6.82842712475+(-2.22044604925E-15)j
  p) {) J5 s% n8 Q; [8 J
$ V, t) C/ w$ Y, M0 U0 h) O我該如何藉由這些值算出SNR及THD呢?