research papers
A series of test calculations of the tangent formula derived from Patterson-function arguments [Rius (1993). Acta Cryst. A49, 406-409] using single-crystal intensity data is presented. This new tangent formula has been compared with the results reported [Sheldrick (1990). Acta Cryst. A46, 467-473] for (a) the tangent formula incorporating the most reliable negative quartets and (b) its extension to the phase-annealing method. The success rate of the new tangent formula is an order of magnitude higher than that of (a), is better than that of (b) when the origin can float in at least one direction, and is similar to that of (b) for other space groups.