Create an unsymmetric 5x5 matrix G by [G,y] = eig(hilb(5)).
G =
   -0.0062    0.0472    0.2142   -0.6019    0.7679
    0.1167   -0.4327   -0.7241    0.2759    0.4458
   -0.5062    0.6674   -0.1205    0.4249    0.3216
    0.7672    0.2330    0.3096    0.4439    0.2534
   -0.3762   -0.5576    0.5652    0.4290    0.2098

    fftn(G)
ans =
  Columns 1 through 4
   3.1673            -0.3843 + 2.3689i  -1.2111 + 0.5080i  -1.2111 - 0.5080i
  -1.8544 + 1.2768i   1.0959 - 0.4675i  -1.5616 + 3.2242i   1.0822 - 0.6208i
   1.3237 - 0.8143i   1.7235 - 3.2026i  -1.1384 - 0.7628i  -1.0977 - 2.4086i
   1.3237 + 0.8143i   0.6113 + 0.3155i  -1.0977 + 2.4086i  -1.1384 + 0.7628i
  -1.8544 - 1.2768i  -0.2499 + 2.0145i   1.0822 + 0.6208i  -1.5616 - 3.2242i
  Column 5
  -0.3843 - 2.3689i
  -0.2499 - 2.0145i
   0.6113 - 0.3155i
   1.7235 + 3.2026i
   1.0959 + 0.4675i

   fft(fft(G),[],2)
   fft(fft(G,[],2))