cachematrix.R

## ---------------------------------------------------------------------
## This function creates a special "matrix" object that can cache its
## inverse.
##
## param[in]   m   The initial value of the matrix (default is empty)
##
## Return: An object
##
## Example of use
## m = matrix(1:4, nrow=2, ncol=2)
## cm <= makeCacheMatrix()
## cm$set(m)
## minv <- cacheSolve(cm)
## m %*% minv   # Should return an identity matrix
## ---------------------------------------------------------------------
makeCacheMatrix <- function(m = matrix()) {
	m_inv <- NULL
	set <- function(y) {
		m <<- y
		m_inv <<- NULL
	}
	get <- function() m
	setinverse <- function(inv) m_inv <<- inv
	getinverse <- function() m_inv
	list(set = set, get = get,
		setinverse = setinverse,
		getinverse = getinverse)
}


## ---------------------------------------------------------------------
## This function computes the inverse of the special "matrix" returned
## by makeCacheMatrix above. If the inverse has already been calculated
## (and the matrix has not changed), then the cachesolve should retrieve
## the inverse from the cache.
##
## param[in]  m  an object created by calling makeCacheMatrix(), and
##               contains an invertible, square matrix.
##
## return  The inverse of the matrix within m.  If m has cached the inverse,
##         then this function will return the cached inverse without
##         recomputing it.
## ---------------------------------------------------------------------
cacheSolve <- function(m) {
	## Return a matrix that is the inverse of 'm'
	inv <- m$getinverse()
	if(!is.null(inv)) {
		message("getting cached inverse")
		return(inv)
	}
	mat <- m$get()
	inv <- solve(mat)
	m$setinverse(inv)
	inv
}