Dear friends,
 I'm recently reading the spatial package, and have vague definitions. Any
help would be greatly appreciated.

1. expcov(r, d, alpha = 0, se = 1)
Arguments
d range parameter  #*?? *Does it mean the distance at which the
semivariogram levels off to the sill ?
alpha  proportion of nugget effect  #*??*alpha = 0 means there isn't nugget
effect,right? it could only be(0,1)? Is there any rule to set it?
se standard deviation at distance zero #*??*how to set this?


2.Kfn(pp, fs, k=100)
Arguments
fs full scale of the plot  #*??*if my pp domain is (0,100)*(0,120), what is
the fs?

3.pplik(pp, R, ng=50, trace=FALSE)
Arguments
R the fixed parameter R  #*??*what does R mean? how to set its value?

4. the following functions are all used to fit the trend surface,what is the
difference ?
surf.gls(spatial): Fits a trend surface by generalized least-squares;
surf.ls(spatial): Fits a trend surface by least-squares;
trmat(spatial): Evaluate trend surface over a grid;

Thanks very much!!

with warm regards,
Wei Chang

	[[alternative HTML version deleted]]


