- There is a Fast Fourier Transform package, do DESCRIBE(FFT) for details. There is also a Fourier Series package. It may be loaded with LOAD(FOURIE). It will also calculate Fourier integral coefficients and has various other functions to do such things as replace all occurrences of F(ARG) by ARG in expression (like changing ABS(a*x+b) to a*x+b). Do PRINTFILE(FOURIE,USAGE,DSK,SHARE1); for a list of the functions included.