cachematrix.R

## The following functions are used to cache the inverse of a matrix.


## The function "makeCacheMatrix" creates a special "matrix", which is really 
## a list containing a function to
## 1. set the value of the matrix
## 2. get the value of the matrix
## 3. set the value of the inverse
## 4. get the value of the inverse

makeCacheMatrix <- function(x = matrix()) {
        inv <- NULL
        set <- function(y) {
                x <<- y
                inv <<- NULL
        }
        get <- function() x
        setinverse <- function(solve) inv <<- solve
        getinverse <- function() inv
        list(set = set, get = get,
             setinverse = setinverse,
             getinverse = getinverse)

}

## The function "cacheSolve" calculates the inverse of the special "matrix" 
## created with the "makeCacheMatrix" function.
## It first checks to see if the inverse has already been calculated. 
## If so, it gets the inverse from the cache and skips the computation. 
## Otherwise, it calculates the inverse of the data and sets the value of the
## inverse in the cache via the setinverse function.

cacheSolve <- function(x, ...) {
        ## Return a matrix that is the inverse of 'x'
        inv <- x$getinverse()
        if(!is.null(inv)) {
                message("getting cached data")
                return(inv)
        }
        data <- x$get()
        inv <- solve(data, ...)
        x$setinverse(inv)
        inv
}