numtricks.R

log.sum <- function(x) {
    m <- max(x)
    r <- sum(exp(x - m))
    return m + log(r)
}

cdist <- function(X, Z) {
    nX <- rowSums(X ** 2)
    nX <- replicate(nrow(Z))
    nZ <- rowSums(Z ** 2)
    nZ <- t(replicate(nrow(X)))

    nX + nZ - 2 (X %*% t(Z))
}