moments_xld ( XLD : : : M11, M20, M02 )

Geometric moments M20, M02, and M11 of contours or polygons.

moments_xld calculates the moments (M20, M02, and M11) of the region enclosed by the contours or polygons XLD. See moments for the definition of these features. The moments are computed by applying Green's theorem using only the points on the contour or polygon, i.e., no region is generated explicitely for the purpose of calculating the features. It is assumed that the contours or polygons are closed. If this is not the case moments_xld will add one point to artificially produce a closed shape. If more than one contour or polygon is passed the results are stored as tuples in which the index of a value corresponds to the index of the respective contour or polygon in XLD.


Parameters

XLD (input_object)
xld(-array) -> object
Contours or polygons to be examined.

M11 (output_control)
real(-array) -> real
Mixed second order moment.

M20 (output_control)
real(-array) -> real
Second order moment along the row axis.

M02 (output_control)
real(-array) -> real
Second order moment along the column axis.


Complexity

Let n be the number of points of the contour or polygon. Then the run time is O(n).


Result

moments_xld returns TRUE if the input is not empty. If the input is empty the behaviour can be set via set_system(::'no_object_result',<Result>:). If necessary, an exception is raised.


Possible Predecessors

gen_contour2_xld, gen_contour_xld, smooth_cont_xld, poly_xld


Alternatives

moments_any_xld


See also

moments_any_xld, area_center_xld, moments, area_center



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