This program computes an angular weights object (AW)
(or a list of AW). If a weights object is passed as argument
("con") the program computes an AW with this element.
If XY is passed, the program first computes a matrix of N x N, where N is the
number of rows in XY, and then uses the matrix as input to compute the AW.
Each element in the weights matrices is then weighted by the
squared cosine of the angle formed with the x positive axis by a line connecting
the pair of points. Note that this method assumes that
the distances in the eco.weight or eco.lagweight object
are projected as great-circle distances (for example,
using latlon = TRUE during weights construction or UTM coordinates for
elements passed with "con", or latlon set TRUE in this function for
a coordinates element passed with XY).
Note also that when angular weights are constructed for XY coordinates,
the output consists of a weights object with values bounded between 0 and 1,
being 1 if the if the direction pointed by the vector V connecting the elements
i, j in the matrix points in the same direction of the reference vector R (with
and angle theta with the positive x axis), and 0 if V is perpendicular to R.