# The functions in this R script work together to calculate

# the inverse of a matrix, and use a cached value if it exists.

# The original matrix must first be initialized and passed

# as an argument to makeCacheMatrix(). Afterwards, the list

# of functions returned by makeCacheMatrix() should be passed

# as an argment to cacheSolve() to retrieve the inverse function.

# makeCacheMatrix

#

# Args:

# 'x' matrix used to calculate inverse - must be square matrix

# Returns:

# A list object containing function pointers to access/set

# the matrix and its inverse matrix.

makeCacheMatrix <- function(x = matrix()) {

i <- NULL

set <- function(y) {

x <<- y

i <<- NULL

}

get <- function() x

setinverse <- function(solve) i <<- solve

getinverse <- function() i

list (set = set, get = get,

setinverse = setinverse,

getinverse = getinverse)

}

# cacheSolve

#

# Args:

# 'x' list object returned by the makeCacheMatrix function

# Returns:

# The cached inverse matrix (if it already exists). Otherwise

# returns the inverse matrix calculated by makeCacheMatrix.

cacheSolve <- function(x, ...) {

## Return a matrix that is the inverse of 'x'

i <- x$getinverse()

if (!is.null(i)) {

message("getting cached inverse")

return(i)

}

data <- x$get()

i <- solve(data, ...)

x$setinverse(i)

i

}