Visual aids in the form of graphs and charts are often used in analysis and design procedures. Commonly, a graph is divided into regions of common characteristics, such as in a soil classification scheme in which a set of properties are located on a chart and the soil classification is given. Although these aids are useful in hand calculations, it is often difficult to implement these charts into a computer code. A general technique is described in this paper which can simplify both implementation and the regional coordinate analysis by the use of an area coordinate method. An example and a short Fortran code are also included to show how this technique can be used.