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Figure 1
Phase refinement by P recycling. (Top) Initial (or updated) phase estimates are used to compute P; (middle) P values are compared with = 2.5 P to impose positivity, thus leading to the constrained P, ; (bottom) new structure-factor estimates are obtained by Fourier transforming P, . CC measures the correlation between observed and new amplitudes. Refinement continues until convergence is reached. This algorithm is also valid for M, the principal difference being substitution of E2 - <E2> by E - <E>.
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