The .raw files are binary versions of the .dat files that have been stored as a sequence of little endian 32-bit IEEE floating point numbers. These binary files are needed by prog1p1.c and may also be listened to using the SoX audio program command
play -c1 -f -b32 -r44100 signalx.rawThe C code fast Fourier transform was adapted from a free FORTRAN code I found on Dr Kifowit's page at Prairie State College. Its simplicity is useful for this project. In situations demanding a hardware optimized fast Fourier transform, the FFTW subroutine library is standard. In particular, FFTW is the library upon which the built-in fast Fourier transforms of MATLAB and Octave are based.