whichhalfplane:
Test Which Side of Infinite Line a Point Falls On
Description
Given an infinite line
and a spatial point location,
determine which side of the line the point falls on.
Usage
whichhalfplane(L, x, y = NULL)
Arguments
L
Object of class "infline" specifying one or more
infinite straight lines in two dimensions.
x,y
Arguments acceptable to xy.coords
specifying the locations of the points.
Value
A logical matrix.
Details
An infinite line $L$ divides the two-dimensional plane into
two half-planes. This function returns a matrix M of logical values
in which M[i,j] = TRUE if the jth spatial point
lies below or to the left of the ith line.