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cachematrix.R

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## Library to cache a matrix using a set of two functions of which one will store

## the matrix to determine whether it has already been cached and one function to inverse the set matrix.

## When the matrix has not been cached or the matrix has been changed, the matrix will be inversed and stored in the cache.

## Created by Stefan Leever @ 2016-02-07

## makeCacheMatrix(x)

## This function sets the initial value for the cached matrix (cm), defines the getter and setter functions and returns a list of functions and values.

## Arguments:

## x: a square matrix.

## Return:

## returns a list with the setter, getter, currently inserted matrix and the original matrix.

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

cm <- NULL

om <<- x

set <- function(x) {cm <<- x}

get <- function() cm

list(set = set, get = get, currentMatrix = x, originalMatrix = om)

}

## cacheSolve(x)

## This function takes the returned list from makeCacheMatrix and inverses the matrix when it's not cached yet.

## If either the matrix has not been cached yet OR the matrix is not the same, it will inverse the matrix and store it in the cache if it's a square matrix.

## Arguments:

## x: makeCacheMatrix list.

## Return:

## returns the inverted matrix.

cacheSolve <- function(x) {

matrix <- x$get()

if (!is.null(matrix)) {

if (identical(x$originalMatrix, x$currentMatrix)) {

return(matrix)

}

matrix <- solve(x$currentMatrix)

x$set(matrix)

return (matrix)

}

# Use the code below to execute the above functions and inverse the matrix.

x <- makeCacheMatrix(matrix(1:4, ncol=2, nrow=2))

y <- cacheSolve(x)