On the application of phase relationships to complex structures. XXI. An extension to the MAGEX procedure

In the previously described MAGEX procedure [Hull, Viterbo, Woolfson & Zhang Shao-Hui (1981). Acta Cryst. A37, 566-572] trial phases found from a ψ map were refined by a parameter-shift process which maximized a function depending on the overall satisfaction of the triple-phase relationships. Advantages have been found in using a different function which has a somewhat stronger physical basis. Two algorithms are described which may be used either for centrosymmetric structures or for individual reflexions which can take only restricted phase values.