cl4_check - check topology of a map file (fortran)

Check the topology of a map file in RLInt CL4 format.

A map file in RLInt CL4 format is topologically valid if and only if:

  1. Only the first polygon (the external boundary) has negative area.
  2. The net area of the entire map is zero.
  3. No segment of any polygon intersects any other nonadjacent segment in the same polygon.
To perform the third test, any causeways, if present, are removed by decomposing the polygon into its subpolygons. Then we make sure that (a) no segment in any subpolygon crosses a nonadjacent segment in the same subpolygon (b) no segment in any subpolygon crosses any segment of any other subpolygon from the same polygon. 

EXECUTION: (on parep2.lbl.gov)
	cd $MDOCS/cl4_check
	module load lang
	f77 -g cl4_check.f  -o cl4_check.exe
	dbx cl4_check.exe
	quit
	cl4_check.exe

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http://merrill.olm.net/mdocs/cl4_check.html 9/17/96
dwmerrill@lbl.gov