cad_parea — compute area of polygon
cad_parea reads from input (standard input if not given) a series of polygon vertex (x,y) coordinate values and writes to output (standard output if not given) the polygon's area. Lines not beginning with a number are silently skipped. Vertices are assumed to be given in counter-clockwise cyclic order.
A hole can be accommodated as a clockwise section connected to the periphery by a line segment traced in both directions.
Disjoint pieces may be connected by a line segment traced in both directions.
Improperly formatted input produces an error message and terminates cad_parea with non-zero exit status.
cad_parea outputs "0" for the area of a degenerate polygon.
This software is Copyright (c) 1991-2016 by the United States Government as represented by U.S. Army Research Laboratory.