# fields, Tools for spatial data
# Copyright 2004-2011, Institute for Mathematics Applied Geosciences
# University Corporation for Atmospheric Research
# Licensed under the GPL -- www.gpl.org/licenses/gpl.html
"Tps" <- function(x, Y, m = NULL, p = NULL, scale.type = "range",lon.lat=FALSE, miles=TRUE,
    ...) {
    x <- as.matrix(x)
    d <- ncol(x)
    if (is.null(p)) {
        if (is.null(m)) {
            m <- max(c(2, ceiling(d/2 + 0.1)))
        }
        p <- (2 * m - d)
        if (p <= 0) {
            stop(" m is too small  you must have 2*m -d >0")
        }
    }
    Tpscall <- match.call()
    if( !lon.lat){
      Tpscall$cov.function <- "Thin plate spline radial basis functions (Rad.cov) "
      Krig(x, Y, cov.function = Rad.cov, m = m, scale.type = scale.type, 
        outputcall = Tpscall, p = p, GCV = TRUE, ...)}
    else{
# use different coding of the radial basis fucntions to use with great circle distance.      
      Tpscall$cov.function <-
        "Thin plate spline radial basis functions (RadialBasis.cov) using great circle distance "
    Krig(x, Y, cov.function = stationary.cov, m = m, scale.type = scale.type, 
        outputcall = Tpscall, GCV = TRUE,
         cov.args=list(Covariance="RadialBasis",M=m, dimension=2, Distance="rdist.earth",
            Dist.args=list(miles=miles)) )}
}