cachematrix.R

## Functions to cache the inverse of a matrix
## Two functions are used to store a matrix and cache its inverse

## makeCacheMatrix sets the matrix, gets the matrix, sets inverse, gets 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)
}


## cacheSolve calculates the inverse of a matrix
## First checks if it has already been calculated - retrieves if so
## Otherwise calculates inverse of matrix using solve()

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