From 353ae6e06d7e3a7c815c5eae7dced69328102133 Mon Sep 17 00:00:00 2001
From: Michele Giusto <mgiusto@users.noreply.github.com>
Date: Tue, 22 Apr 2014 01:24:05 +0200
Subject: [PATCH] Implemented the requested functions

---
 cachematrix.R | 54 ++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 45 insertions(+), 9 deletions(-)

diff --git a/cachematrix.R b/cachematrix.R
index a50be65aa44..ae03f403b56 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -1,15 +1,51 @@
-## Put comments here that give an overall description of what your
-## functions do
-
-## Write a short comment describing this function
+## makeCacheMatrix and cacheSolve allows to create an object that stores a matrix with its inverse, in order to reuse the latter
+## value more times without having to recompute it.
 
+## makeCacheMatrix creates an object that store a matrix, passed as input parameter, with its inverse (computed later). It allows
+## to reuse the inverse by caching its value, saving computing time when the inverse it is know to be required more times.
+## The returned object has 4 functions:
+### set: set the matrix to be cached
+### get: get the cached matrix
+### setinverse: cache the computed inverse of the cached matrix
+### getinverse: get the computed inverse, without having to recompute it
 makeCacheMatrix <- function(x = matrix()) {
-
+  inverse <- NULL
+  set <- function(y) {
+    matrix <<- y
+    inverse <<- NULL
+  }
+  get <- function() x
+  setinverse <- function(inv) inverse <<- inv
+  getinverse <- function() inverse
+  list(set = set, get = get,
+       setinverse = setinverse,
+       getinverse = getinverse)
 }
 
+## cacheSolve computes and stores the value of the inverse of the matrix cached in an object created by the makeCachedMatrix 
+## function (passed as argument), storing it in the object itself. If the inverse has been already computed, it returns the value
+## directly. Otherwise, the value is computed, stored and returned to the caller of the function.
+cacheSolve <- function(x) {
+  inverse <- x$getinverse()
+  if(!is.null(inverse)) {
+    message("getting cached data")
+    return(inverse)
+  }
+  matrix <- x$get()
+  inverse <- solve(matrix)
+  x$setinverse(inverse)
+  inverse
+}
 
-## Write a short comment describing this function
 
-cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
-}
+# ## unit tests
+# mat=matrix(c(3,1,2,7,8,9,4,5,6),nrow=3,ncol=3)
+# matInv = solve(mat)
+# cacheMat = makeCacheMatrix(mat)
+# cacheMat$get()
+# if (!all(matInv == cacheSolve(cacheMat)))
+#   message("test not passed")
+# if (!all(matInv ==  cacheMat$getinverse()))
+#   message("test not passed")
+# if (!all(matInv ==  cacheSolve(cacheMat)))
+#   message("test not passed")