https://github.com/cran/pracma
Tip revision: 708a2ad382a163d1eef5af0665e3ae2aad200ced authored by HwB on 21 March 2013, 00:00:00 UTC
version 1.4.5
version 1.4.5
Tip revision: 708a2ad
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]
}