FMCW Radar Signal Processing based on MIT Open Course
The inverse discrete Fourier transformation is pretty much the same as the discrete Fourier transformation.  This also applies to the fast Fourier transformation.
The MATLAB code you show uses the inverse fast Fourier transformation (function ifft.)
I can't explain the rest of the code.  It seems to have been written for maximum obscurity, and I don't understand the concepts used well enough to decipher it.