https://github.com/cran/fields
Tip revision: 6769ffc81115fbf0bf7d9c566cf7ac81be0049dc authored by Doug Nychka on 25 July 2005, 00:00:00 UTC
version 3.04
version 3.04
Tip revision: 6769ffc
Krig.df.to.lambda.r
"Krig.df.to.lambda" <-
function (df, D, guess = 1, tol = 1e-05)
{
if (is.list(D)) {
D <- D$matrices$D
}
if (is.na(df))
return(NA)
if (df < sum(D == 0)) {
warning("df too small to match with a lambda value")
return(NA)
}
if (df > length(D)) {
warning(" df too large to match a lambda value")
return(NA)
}
l1 <- guess
for (k in 1:25) {
tr <- sum(1/(1 + l1 * D))
if (tr <= df)
break
l1 <- l1 * 4
}
l2 <- guess
for (k in 1:25) {
tr <- sum(1/(1 + l2 * D))
if (tr >= df)
break
l2 <- l2/4
}
info <- list(D = D, df = df, N = length(D))
out <- bisection.search(log(l1), log(l2), Krig.fdf, tol = tol,
f.extra = info)$x
+exp(out)
}