Given two point patterns in multi-dimensional space,
this function computes the Euclidean distance from each point
in the first pattern to each point in the second pattern,
and returns a matrix containing these distances.
This is a method for the generic function crossdist
for three-dimensional point patterns (objects of class "ppx").
This function expects two multidimensional
point patterns X and Y, and returns the matrix
whose [i,j] entry is the distance from X[i] to
Y[j].
By default, both spatial and temporal coordinates are extracted.
To obtain the spatial distance between points in a space-time point
pattern, set temporal=FALSE.