uni/sose2021/r/w07/P07-1.R

# Josua Kugler, Christian Merten

mem_near <- function(f_in) {
    memo <- list(input=c(), value=c())
    function(x, nearest) {
        if (!nearest) {
            memo$input <<- c(memo$input, x)
            y <- f_in(x)
            memo$value <<- c(memo$value, y)
            return(y)
        }
        memo$value[apply(outer(memo$input, x, function(a, b)  abs(a-b)), 2, which.min)]
    }
}