Abstract

<h2>Acta Crystallographica Section A</h2><h3>Crystal Physics, Diffraction, Theoretical and General Crystallography</h3><h3>0567-7394</h3> <h2>research papers</h2> Volume 33 Part 1 Page 4 January 1977 <h2>Computer science and crystallography</h2> S. C. Abrahams Acta Cryst. (1977). A33, 4 Computer Science and Crystallography Information generated within one discipline often re- mains unknown in others for extended periods, despite the possibility of clear and sometimes urgent relevance, as illustrated by two important examples taken from the history of crystallography. The method of least squares has been known to mathematicians since Legendre's book was published in 1806, and had been regularly taught to classes in numerical data analysis by E. Whittaker and others since 1913 or earlier. Until E. W. Hughes introduced the method into crystallog- raphy in 1941, crystal-structure refinement was car- ried out exclusively by various Fourier techniques. Least-squares refinement remained uncommon as late as 1950, partly owing to computational difficulties but mostly to general unfamiliarity with the method. The now widely recognized importance of the method is easily verified by perusal of Acta Crystallographica Section B in which it is used in nearly every paper. The second example comes from experimental crys- tallography. Until the late 1950's, the principal counter used in X-ray diffractometry