dyn.load("mat.so")


sum1 <- function(matrix) {
    result <- 0
    for (i in seq_len(nrow(matrix))) {
        for (j in seq_len(ncol(matrix))) {
            result <- result + matrix[i, j]
        }
    }
    return(result)
}

sum2 <- function(matrix) {
    nrow <- nrow(matrix)
    ncol <- ncol(matrix)
    result <- .C("c_sum_matrix", as.double(matrix), as.integer(nrow), as.integer(ncol), result = double(1))$result
    return(result)
}