diff --git a/.gitignore b/.gitignore
new file mode 100644
index 00000000000..807ea251739
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+.Rproj.user
+.Rhistory
+.RData
diff --git a/cachematrix.R b/cachematrix.R
index a50be65aa44..a53a546b782 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -1,15 +1,72 @@
-## Put comments here that give an overall description of what your
-## functions do
+## Programming assignment 2
+##
+## > m <- matrix(rnorm(49),7,7)
+## > mc <- makeCacheMatrix(m)
+## > cacheSolve(mc)
+## [,1]        [,2]      [,3]       [,4]        [,5]
+## [1,] -0.2335268  0.32422911 0.6239005  0.2368416 -0.36826412
+## [2,] -0.4776660  0.06646721 0.5249364 -1.0634309  0.04139137
+## [3,]  0.1285453 -1.30284238 1.0972079 -2.3344796  0.02208996
+## [4,] -0.2068005 -0.74517115 0.2454044  0.1984123 -0.18916633
+## [5,] -0.1402871 -0.72239385 1.3482179 -1.7596189 -0.49403317
+## [6,]  0.3558382 -0.82380599 0.1844959 -0.4698125 -0.82707022
+## [7,]  0.4052904 -0.83673069 0.8795818 -2.3184046  0.18261628
+## [,6]       [,7]
+## [1,] -0.18516499  0.9944101
+## [2,] -0.23073671  0.4691068
+## [3,]  0.07649743  0.3722228
+## [4,] -0.18435024 -0.1223557
+## [5,]  0.35501462  0.3422012
+## [6,]  0.24631449 -0.5766368
+## [7,]  0.13758246 -0.0364764
+## > head(cacheSolve(mc),3)
+## using cached data
+## [,1]        [,2]      [,3]       [,4]        [,5]
+## [1,] -0.2335268  0.32422911 0.6239005  0.2368416 -0.36826412
+## [2,] -0.4776660  0.06646721 0.5249364 -1.0634309  0.04139137
+## [3,]  0.1285453 -1.30284238 1.0972079 -2.3344796  0.02208996
+## [,6]      [,7]
+## [1,] -0.18516499 0.9944101
+## [2,] -0.23073671 0.4691068
+## [3,]  0.07649743 0.3722228
 
-## Write a short comment describing this function
 
+## create a special kind of matrix that will cache the result
+## of the solve() function
 makeCacheMatrix <- function(x = matrix()) {
-
+  # we're going to use that to cache the inverse of the
+  # matrix provided in parameters
+  inverse <- NULL
+  # cache the value of the matrix
+  set <- function(y) {
+    x <<- y
+    # we've just reset the original matrix, so initialize
+    # the inverse to NULL, so we don't return values from 
+    # previous computations
+    inverse <<- NULL
+  }
+  # return the cached value of the original matrix 
+  get <- function() x
+  # return the inverse of the cached data
+  getinverse <- function() {
+    # check if we have already computed the inverse 
+    if (!is.null(inverse)) {
+      # YAY ! just return the value we have already computed
+      message("using cached data")      
+      return(inverse)
+    }
+    # else, solve the matrix, store the result and return it
+    inverse <<- solve(x)
+    inverse
+  }
+  # return a vector containing the different "member" functions
+  list(set = set, get = get, getinverse = getinverse)
 }
 
 
-## Write a short comment describing this function
-
+## solve a matrix x, using cached data if possible
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+  # just call the getinverse() 'member' function, retrieving 
+  # the cached solve(result) if it has already been computed
+  x$getinverse()
 }