https://github.com/cran/fields
Tip revision: ce722edae3c1b9e1af2985ce3500b11058facf0e authored by Doug Nychka on 24 August 2006, 01:46:17 UTC
version 3.04
version 3.04
Tip revision: ce722ed
D4transform.image.R
"D4transform.image" <-
function (x, inv = FALSE, transpose = FALSE, cut.min = 8)
{
if (transpose)
inv <- !inv
n <- dim(x)[1]
m <- dim(x)[2]
if (n > m) {
flip <- TRUE
temp <- t(x)
n <- dim(temp)[1]
m <- dim(temp)[2]
}
else {
flip <- FALSE
temp <- x
}
if (n > m)
stop(" number of columns of x must >= to number of\nrows")
nn <- n
mm <- m
if (!inv) {
while (nn > cut.min) {
temp[1:nn, 1:mm] <- WD42d(temp[1:nn, 1:mm])
nn <- nn/2
mm <- mm/2
}
}
if (inv) {
NN <- n
MM <- m
while (NN > cut.min) {
NN <- NN/2
MM <- MM/2
}
nn <- NN * 2
mm <- MM * 2
while (nn <= n) {
temp[1:nn, 1:mm] <- WD42di(temp[1:nn, 1:mm])
nn <- nn * 2
mm <- mm * 2
}
}
if (flip) {
return(t(temp))
}
else {
return(temp)
}
}