Calculate the covariance matrix for the difference between two K-functions. Also return the contribution to the variance for each of the two point patterns,
khvc(pts1, pts2, poly, s)An object containing the case locations.
An object containing the control locations.
A polygon enclosing the locations in pts1 and pts2
A vector of distances at which the calculation is to be made.
A list with four components:
The upper triangle of the covariance matrix.
The variance of Khat for the cases
The variance of Khat for the controls
The covariance of Khat for the cases and Khat for controls.
Rowlingson, B. and Diggle, P. 1993 Splancs: spatial point pattern analysis code in S-Plus. Computers and Geosciences, 19, 627-655; the original sources can be accessed at: http://www.maths.lancs.ac.uk/~rowlings/Splancs/. See also Bivand, R. and Gebhardt, A. 2000 Implementing functions for spatial statistical analysis using the R language. Journal of Geographical Systems, 2, 307-317.