Understanding the gp:pointEqual, gp:rtos2, and gp:zeroSmallNum Functions

These three functions are required to get around one of the quirks of programming in an AutoCAD system, which, as you are well aware, allows you a great deal of precision. Occasionally, though, numbers are not quite precise enough, due to the rounding up or down of floating point values defining geometric positions. You must be able to compare one set of points with other points, so you must deal with these cases.

1.0e-017? This number is *almost*
zero, but when you are comparing it to zero within a LISP program,
*almost* does not count.

1.0e-017 is
not quite zero. The *gp:pointEqual*, *gp:rtos2*, and
*gp:zeroSmallNum* functions handle
any discrepancies in rounding when comparing point lists.

*gppoly.lsp*.