Fourier_trans.c: Fourier transform using fftw library
ch_st_hdrs.c: change station header using SACIO library
chst.c: change station header by loading external command in SAC
cov_mat_an.c: calculate short time covariance matrix (incomplete)
cut.c: cut using SAC library
diagonalize.c: diagonalize matrix using lapack library
distaz.c: stand alone sac-102.0/src/ucf/distaz.c
hdroutput.c: print SAC headers pretty
matlab_c_api.c: change stla, stlo SAC headers using MatLab-C interface (incomplete)
ms_merge.c: merge MSEED file traces to single SAC file
ppsd.c: C version obspy.signal.spectral_estimation.PPSD, translated to C
proj_geod.c: calculate distance, azimuth and back azimuth using PROJ C library
vhdrupgrade.c: upgrade defined SAC headers' version 6->7
vhdrupgrade_undefined.c: upgrade undefined SAC headers' version 6->7