The program SAPI and its applications. Pt. 3

Optimization has been made of the program SAPI for automatic solution of structures having pseudotranslational symmetry. This includes: (1) Floating default cutoff of E's; (2) automatic and user-adjustable balance between the number of systematically strong reflections and that of the systematically weak ones; (3) R factors for reflection subsets corresponding to the 'strong' group and the 'weak' groups. Examples on solving structures with pseudo-translational symmetry are discussed in detail. They include known as well as unknown structures and centrosymmetric as well as non-centrosymmetric structures, all of which can be solved starting from a default run of SAPI. (orig.)