Absorption corrections: procedures for checking crystal shape, crystal orientation, and computer absorption programs

Practical details for obtaining an accurate description of the shape of a crystal in a laboratory coordinate system for input to a general absorption program are given. Remarks on practical ways to test an absorption program, together with some comparisons of the accuracy of several widely distributed programs, are made. Comparisons are made with results derived analytically for a contrived crystal which lacks a morphological center of symmetry.