Parallel Curves

Simple program to generate the inner and outer parallel curves in rectangular coordinates. inner parallel is toward the center of curvature and outer parallel is away from the center of curvature. Use option flag1=0 to keep the parallels on the side sides (disregarding concavity). The Input the x, y coordinate pairs and distance between the curve and the parallels and the option to make a plot.

Parallel curves are related to the involute, evolute, and envelope. Program can easily be modified to generate the evolute by replacing d with R in lines 254-270.