The equations used are X = R { cos(?o) *?? - sin(?o) * ?? *?? } Y = R { ?? + 0.5 * sin(?o) * cos(?o) * ?? * ?? }, where R is in kilometers per degree on the mean radius sphere (computed by the program), ?? is the latitude minus the average latitude ?o, and ?? is the longitude minus the average longitude ?o The X and Y coordinates are given in kilometers.
The simplicity of the system can be seen by rewriting it as X = a01 * ?? + a12 * ?? * ?? Y = a10 * ?? + a22 * ?? * ??. The distortion is also easily calculated from these equations.