cachematrix.R

## R programming assignmment 2
## ----------------------------
## 

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

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

}


## The following function calculates the inverse of the special "matrix"
## created with the above function. However, it first checks to see if the
## inverse has already been calculated. If so, it `get`s the inverse from the
## cache and skips the computation. Otherwise, it calculates the inverse of
## the matrix and sets this value in the cache via the `setinverse`
## function.


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