# Freint, an integration routine calculating Fresnel diffraction

## Description

Title of program: FREINT Catalogue Id: ACUB_v1_0 Nature of problem FREINT evaluates the integral A(x) exp(i q (x'-x)^2) dx [i= (-1)^1/2, x = xi,xf] occurring in optical transfer theory. By application of this integral the wave amplitude A(t+d;x') at a plane z = t+d can be calculated on some premises from the amplitude field A(t;x), e.g. in electron microscopy if an object is imaged in a defocussed mode (catchword : Fresnel diffraction). A(x) is given by a complex vector. CORRECTION SUMMARY: Vol:Year:Page 0:unpublished:unpublished "000ACORRECTION 27/11/78" "Unpublished correction to FREINT: an integration routine calculating Fresnel diffraction." W.J. Gruschel Note: correction instructions are contained in source code Versions of this program held in the CPC repository in Mendeley Data ACUB_v1_0; FREINT; 10.1016/0010-4655(79)90086-9 This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2019)