https://github.com/cran/pracma
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Tip revision: c79a04b5074656b36e591191eb8137b70a349932 authored by Hans W. Borchers on 30 June 2014, 00:00:00 UTC
version 1.7.0
Tip revision: c79a04b
conv.R
##
##  c o n v . R  Polynomial Convolution
##


conv <- function(x, y) {
    if ( (!is.vector(x, mode="numeric") && !is.vector(x, mode="complex")) ||
         (!is.vector(y, mode="numeric") && !is.vector(y, mode="complex")) )
        stop("Arguments 'x' and 'y' must be real or complex vectors.")

    lx <- length(x)
    ly <- length(y)
    n <-  lx +  ly - 1
    z <- fft(fft(c(x, rep(0, n - lx))) * fft(c(y, rep(0, n - ly))),
             inverse = TRUE) / n

    if (is.numeric(x) && is.numeric(y))
        z <- Re(z)
    return(z)
}
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