SPACER: a program to display space-group information for a conventional and nonconventional coordinate system

SPACER is a personal computer program developed to help one obtain different information on space groups. Based on matrix manipulation and a small number of conventions and data, it allows generation of symmetry operations and Wyckoff positions in the form contained in International Tables for Crystallography [(1983). Vol. A. Dordrecht: Reidel; referred to herein as ITA83]. Implemented algorithms are used for shifting or transforming a coordinate system, analysing the matrix form of a motion, creating tables of special position permutations [Boyle & Lawrenson (1973). Acta Cryst. 29, 353-357] and so on. The aim of this work was to obtain a flexible tool for teaching space groups in crystallography. The work describes the main features of the program and results of comparison of generated symbols with those contained in ITA83.