diff --git a/cachematrix.R b/cachematrix.R
index a50be65aa44..accc87cda92 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -1,15 +1,64 @@
-## Put comments here that give an overall description of what your
-## functions do
+## Inverting a matrix can be computationnally intensive
+## If we invert the same matrix multiple times, it can be worth caching the result
 
-## Write a short comment describing this function
+##        X = matrix(data=c(2,0,0,2),nrow=2,ncol=2)
+##        M = makeCacheMatrix(X)
+## Creates a special matrix M and caches its inverse
+##
+##        N = cacheSolve(M)
+## computes the inverse of the special matrix M
+## if the inverse has already been computed
+## gets it from cache
 
-makeCacheMatrix <- function(x = matrix()) {
+## Mostly taken from the example "Caching the Mean of a Vector"
 
-}
+## this function creates a special matrix, which is a list containing
+## a function to
+## set the value of the matrix
+## get the value of the matrix
+## set the value of the inverse
+## get the value of the inverse
+
+makeCacheMatrix <- function(X = matrix()) {
+
+	# A contains the value of the inverse, if cached
+
+	A <- NULL
 
+	# set: set value of the matrix, set inverse to NULL
+	set <- function(Y) {
+		X <<- Y
+		A <<- NULL
+	}
+
+	# get: get the value of the matrix
+	get <- function() X
+
+	# set and get value of the inverse
+	setInverse <- function(B) A <<- B
+	getInverse <- function() A
+	list(set = set, get = get,
+		setInverse = setInverse,
+		getInverse = getInverse)
+}
 
-## Write a short comment describing this function
+## this function returns the inverse of a special matrix created
+## with the makeCacheMatrix function
+## either by computing it or by getting the result from cache
 
-cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+cacheSolve <- function(X, ...) {
+        
+	# first, try to get inverse from cache
+	M <- X$getInverse()
+	if(!is.null(M)) {
+		# if stored inverse is not null, it has already been computed
+		# -> get value from cache
+		message("getting cached data")
+		return(M)
+	}
+	# if stored inverse is null, compute the inverse and store it for eventual later usage
+	data <- X$get()
+	M <- solve(data, ...)
+	X$setInverse(M)
+	M
 }