Coursera

makeCacheMatrix <- function(x = matrix()) {
  inv <- NULL
  # set the value of the matrix
  set <- function(y) {
    x <<- y
    inv <<- NULL
  }
  # get the value of the matrix
  get <- function() x
  # set the value of the inverse
  setinverse <- function(inverse) inv <<- inverse
  # get the value of the inverse
  getinverse <- function() inv
  # return:
  list(set = set, get = get,
       setinverse = setinverse,
       getinverse = getinverse)
  
  cacheSolve <- function(x, ...) {
    inv <- x$getinverse() # function() inv
    if(!is.null(inv)) {
      message("getting cached data")
      return(inv) # return ends the function
    }
    data <- x$get() # function() x
    inv <- solve(data, ...) # calculates the inverse and stores it as inv
    x$setinverse(inv) # function(inverse) inv <<- inverse
    inv
  }