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Expressions for first and second derivatives in least‐squares refinements including extinction
Author(s) -
Spackman M. A.
Publication year - 1987
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889887086758
Subject(s) - extinction (optical mineralogy) , isotropy , least squares function approximation , mathematics , mathematical analysis , optics , physics , statistics , estimator
Compact expressions are given for first and second derivatives necessary for inclusion of the Becker–Coppens isotropic extinction model in a least‐squares procedure. Derivatives with respect to a scale factor, a structural parameter, and the two extinction parameters g and ρ are considered, for refinements on | F | and | F | 2 .