x <- c(0,0,0,100,0,0,0) y <- c(0,0,1, 2 ,1,0,0)/4 zapsmall(convolve(x,y)) # *NOT* what you first thought. zapsmall(convolve(x, y[3:5], type="f")) # rather x <- rnorm(50) y <- rnorm(50) # Circular convolution *has* this symmetry: all.equal(convolve(x,y, conj = FALSE), rev(convolve(rev(y),x))) n <- length(x <- -20:24) y <- (x-10)^2/1000 + rnorm(x)/8 Han <- function(y) # Hanning convolve(y, c(1,2,1)/4, type = "filter") plot(x,y, main="Using convolve(.) for Hanning filters") lines(x[-c(1 , n) ], Han(y), col="red") lines(x[-c(1:2, (n-1):n)], Han(Han(y)), lwd=2, col="dark blue")