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，
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& }' |7 f. V" t6 I) t& s% DX[0] = 24+(0)j
. ]5 ]* D! m5 hX[1] = -6.82842712475+(-1.33226762955E-15)j
% b, X: |! m$ g/ z9 XX[2] = 3.09539720245E-17+(0)j
7 c2 P9 }, J* y$ q$ |. xX[3] = -1.17157287525+(2.88657986403E-15)j
4 H6 [2 B' H7 jX[4] = 0+(-4.89842541529E-16)j
X[5] = -1.17157287525+(-2.44249065418E-15)j
X[6] = -9.86282453277E-15+(-6.66133814775E-16)j
  m2 s/ s% y  ?1 |5 UX[7] = -6.82842712475+(-2.22044604925E-15)j
" b6 Y& ~# E* R8 X6 d7 `: B
9 @/ l4 I* @/ b$ g我該如何藉由這些值算出SNR及THD呢?