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csgchk

Check validity of Geometry Description matrix

Syntax

gstat = csgchk(gd,xlim,ylim)
gstat = csgchk(gd)

Description

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.

See Also

Introduced before R2006a