function?y?=?ffttx（x）
%FFTTX??Textbook?Fast?Finite?Fourier?Transform.
%????FFTTX（X）?computes?the?same?finite?Fourier?transform?as?FFT（X）.
%????The?code?uses?a?recursive?divide?and?conquer?algorithm?for
%????even?order?and?matrix-vector?multiplication?for?odd?order.
%????If?length（X）?is?m*p?where?m?is?odd?and?p?is?a?power?of?2?the
%????computational?com