INSTAT: a program for computing non-ideal probability density functions of |E|

The purpose of this program is to evaluate probability density functions (p.d.f.s) of the magnitude of the normalized structure factor |E| for the space groups of the triclinic, monoclinic and orthorhombic systems, and for any chemical composition of the asymmetric unit, assuming that the atoms are located in general positions. The p.d.f.s are computed by the Fourier and Fourier-Bessel methods [see e.g. Shmueli (2012). J. Appl. Cryst. 45, 389-392]. The p.d.f.s evaluated are scaled together with the histogram of observed |E| values and discrepancy criteria are computed. In addition to the above non-ideal p.d.f.s, the ideal p.d.f.s [Wilson (1949). J. Appl. Cryst. 2, 318-321] are also computed and prepared for comparison with an experimental histogram.