Introduction - If you have any usage issues, please Google them yourself
DIT- FFT subroutine FFT length of 2m, m is a positive integer. FFT output on the importation of complex array. Xr which kept real signal sequence, the signal sequence xi kept the imaginary part. If the signal is less than the length of N, and the need to xr xi behind complement 0, The results of x (k) the real and imaginary parts were still stored in the array xr and xi China.