Anyone reading this list familiar with the 'fields' package?

I am trying to use the 'Tps' function, which is a wrapper for 'Krig'.

I've used this function many times, but have generally not used covariates.

There is an argument 'Z' that can be added to include fixed effects in the
model.

What I don't know is how 'Z' should be structured.

I've tried 'Z = model.matrix(~ 0 + date + date:machine)' where 'date' and
'machine' are factors. 'Machine' is nested within 'date'.

This results in an error here:

# excerpt from Krig
  else {
        mZ <- ncol(out$ZM)
        if (verbose) {
            cat("ZM", out$ZM, fill = TRUE)
            cat("mZ", mZ, fill = TRUE)
            cat("nt", out$nt, fill = TRUE)
        }
        out$ind.drift <- c(rep(TRUE, out$nt - mZ), rep(FALSE,
            mZ))
    }

The problem is that 'mZ' is larger than 'out$nt'.

Should 'Z' be given as a model matrix? A single vector? A formula?
Documentation does not specify.

THK


-- 
Timothy H. Keitt
http://www.keittlab.org/

	[[alternative HTML version deleted]]

