An Algorithm for Plotting Contours in Arbitrary Planar Regions

摘要

The document describes an algorithm for generating contour plots of a function defined on an arbitrary planar region. The algorithm contains three features not normally found in contour plotting routines. Any planar region which can be enclosed by a single boundary curve that does not cross itself can be treated. Function values can be specified for any arbitrary distribution of points in the region. The region specified by the data points is subdivided into a collection of adjacent triangles whose union is the entire region. This technique is useful for problems other than contour plotting, in particular for finite element calculations. The algorithm may be used for any application which requires a graphical display of a function f(x,y) of two variables. A computer program which implements the contour plotting algorithm is also described in this document. The program is written in ASA Standard FORTRAN and descriptions of the plotting commands used are included so that the reader may easily convert the program to work with any plotting equipment. Included as appendices are test examples for the plotting routine and a computer listing of the FORTRAN source decks. (Author)