https://github.com/cran/pracma
Tip revision: 3fdb68cc842f2ab3b59608f8e04d495763584f78 authored by Hans W. Borchers on 27 November 2015, 12:07:10 UTC
version 1.8.8
version 1.8.8
Tip revision: 3fdb68c
fft.R
##
## f f t . R Fourier Transform
##
ifft <- function(x) {
if (length(x) == 0)
return(c())
if ( (!is.vector(x, mode="numeric") && !is.vector(x, mode="complex")))
stop("Argument 'x' must be real or complex vector.")
fft(x, inverse = TRUE) / length(x)
}
fftshift <- function(x) {
stopifnot(is.double(x) || is.complex(x) || is.integer(x))
if (!is.vector(x))
stop("Argument 'x' must be a real or complex vector.")
m <- length(x)
p <- ceiling(m/2)
idx <- c((p+1):m, 1:p)
x[idx]
}
ifftshift <- function(x) {
stopifnot(is.double(x) || is.complex(x) || is.integer(x))
if (!is.vector(x))
stop("Argument 'x' must be a real or complex vector.")
m <- length(x)
p <- floor(m/2)
idx <- c((p+1):m, 1:p)
x[idx]
}