The POLY_AREA function returns the area of a polygon given the coordinates of its vertices.
It is assumed that the polygon has n vertices with n sides and the edges connect the vertices in the order:
[(x1,y1), (x2,y2), ... , (xn,yn), (x1,y1)]
such that the last vertex is connected to the first vertex.
This routine is written in the IDL language. Its source code can be found in the file poly_area.pro in the lib subdirectory of the IDL distribution.
Syntax
Result = POLY_AREA( X, Y [, /DOUBLE] [, /SIGNED] )
Return Value
If either of the input arguments is double-precision or if the DOUBLE keyword is set, the result is a double-precision value, otherwise, the result is single-precision.
Arguments
X
An n-element vector of X coordinate locations for the vertices.
Y
An n-element vector of Y coordinate locations for the vertices.
Keywords
DOUBLE
Set this keyword to use double-precision for computations and to return a double-precision result. Explicitly set DOUBLE=0 to use single-precision for computations and to return a single-precision result. By default, if either of the arguments to POLY_AREA is double-precision, computations are done in double-precision; if both arguments are single-precision, computations are done in single-precision.
SIGNED
If set, returns a signed area. Polygons with edges traversed in counterclockwise order have a positive area; polygons traversed in the clockwise order have a negative area.
Version History
See Also
POLYFILLV