cachematrix.R

## Calculate the inverse of a matrix and cache it

## Setter and getter function: creates an R object (matrix) and its inverse
# 1. set the value of the matrix
# 2. get the value of the matrix
# 3. set the value of the inverse of the matrix
# 4. get the value of the inverse of the matrix

makeCacheMatrix <- function(x = matrix()) {
    m <- NULL
    set <- function(y) {
        x <<- y
        m <<- NULL
    }
    get <- function() x
    setinv <- function(solve) m <<- solve # doesn't seem to matter to call "solve" or "inverse" here
    getinv <- function() m
    list(set = set, get = get,
         setinv = setinv,
         getinv = getinv)
}


## Cache the inverse. 
# If value already exists, print a message and retrieve the inverse 

cacheSolve <- function(x, ...) {
    m <- x$getinv()
    if(!is.null(m)) {
        message("getting cached data")
        return(m)
    }
    data <- x$get()
    m <- solve(data, ...)
    x$setinv(m)
    m
}