Fast Fourier transform calculation of electron density maps.

This chapter has described the mathematical basis of the fast Fourier transform as applied to the calculation of crystallographic Fourier syntheses. The relationship between real space and reciprocal space symmetry operators has been described. Finally, program organizations have been presented for performing general crystallographic Fourier transforms on computer systems ranging from the very largest systems down to minicomputers. Programs are available from the author, written in FORTRAN IV and in Ratfor, which are suitable for building blocks in these program designs.