On the application of phase relationships to complex structures. XXV. TRITAN - or recycled failure

Even when direct methods fail to give a clear solution, E maps from some of the phase sets obtained contain correctly oriented fragments. It is shown that such information from several phase sets can be amalgamated by an automatic procedure to give estimates of the values of three-phase invariants. These estimates are incorporated into a modified tangent formula which is used in a new run of a multisolution direct-methods procedure. Tests of the total process, called TRITAN, reveal that it is very effective in determining structures which otherwise would not be found routinely.