An interactive program for the interpretation and simulation of Laue patterns

An interactive Fortran IV program is described which allows the orientation matrix of a crystal to be determined and refined without ambiguity, from a transmission or reflection Laue photograph. The indexing method is that of Riquet & Bonnet [J. Appl. Cryst. (1979), 12, 39-41] applied to a small number of data (less than ten) and adapted for interactive use. The verification of calculated solutions or even the trial-and-error search for the right solution is made by means of the visual comparison between the experimental diagram and simulated patterns displayed on a graphic screen. In addition, the rotation angles for setting the crystal to any new orientation may be computed.