Check validity of Geometry Description matrix
gstat = csgchk(gd,xlim,ylim)
gstat = csgchk(gd)
gstat = csgchk(gd,xlim,ylim) checks if the solid objects
in the Geometry Description matrix gd are valid, given optional real
numbers xlim and ylim as current length of the
x- and y-axis, and using a special format for
polygons. For a polygon, the last vertex coordinate can be equal to the first one, to
indicate a closed polygon. If xlim and ylim are
specified and if the first and the last vertices are not equal, the polygon is
considered as closed if these vertices are within a certain “closing
distance.” These optional input arguments are meant to be used only when calling
csgchk from the PDE Modeler app.
gstat = csgchk(gd) is identical
to the preceding call, except for using the same format of gd that
is used by decsg. This call is recommended when
using csgchk as a command-line function.
gstat is a row vector of integers that indicates
the validity status of the corresponding solid objects, i.e., columns,
in gd.
For a circle solid, gstat = 0 indicates that
the circle has a positive radius, 1 indicates a
nonpositive radius, and 2 indicates that the circle
is not unique.
For a polygon, gstat = 0 indicates that the
polygon is closed and does not intersect itself, i.e., it has a well-defined,
unique interior region. 1 indicates an open and
non-self-intersecting polygon, 2 indicates a closed
and self-intersecting polygon, and 3 indicates
an open and self-intersecting polygon.
For a rectangle solid, gstat is identical
to that of a polygon. This is so because a rectangle is considered
as a polygon by csgchk.
For an ellipse solid, gstat = 0 indicates
that the ellipse has positive semiaxes, 1 indicates
that at least one of the semiaxes is nonpositive, and 2 indicates
that the ellipse is not unique.
If gstat consists of zero entries only, then gd is
valid and can be used as input argument by decsg.