Simple algorithm for a maximum-likelihood SAD function.
Recently, the multivariate complex normal distribution has been used to develop a maximum-likelihood probability function for single-wavelength anomalous diffraction phasing and refinement of heavy-atom parameters [Pannu & Read (2004), Acta Cryst. D60, 22-27]. The function accounts explicitly for the correlations between the observed and calculated Friedel mates and their errors. However, the method of derivation of the equation described by Pannu & Read (2004) leads to a complicated likelihood expression that suffers from a number of algorithmic limitations. Here, an alternative derivation of the P(SAD) function is described that leads to simplified algorithmic requirements and that allows an intuitive understanding of the expression.
McCoy
Airlie J
AJ
University of Cambridge, Department of Haematology, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, England.
Storoni
Laurent C
LC
Read
Randy J
RJ
D000465:Algorithms; D043542:DNA, Z-Form / Q000737:chemistry; D016013:Likelihood Functions
D043542:DNA, Z-Form