cachematrix.R

## A special matrix-like object that can cache the result of the 
## computationally expensive solve() operation (which calculates
## the inverse of a matrix).

## This file was created for Programming Assigment 2 of the 
## Coursera course "R Programming" (rprog-007) by Edwin Rijgersberg.


## Create a matrix-like list object, containing the functions to
## get and set the matrix value, and get and set the inverse.

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


## If the inverse of the matrix has not yet been calculcated before,
## calculated and cache it. If it has been, simply return the cached
## value.
## It is assumed that the matrix supplied is always invertible.

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