From 07026f8fd75995178dcd9d9d2cbe2883cc827946 Mon Sep 17 00:00:00 2001
From: domangi <domenico.angilletta@gmail.com>
Date: Sat, 20 Dec 2014 14:20:16 +0100
Subject: [PATCH 1/2] added function body to makeCacheMatrix and cacheSolve

---
 cachematrix.R | 47 ++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 40 insertions(+), 7 deletions(-)

diff --git a/cachematrix.R b/cachematrix.R
index a50be65aa44..a1cc04b3574 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -1,15 +1,48 @@
-## Put comments here that give an overall description of what your
-## functions do
+## makeCacheMatrix(X = matrix()) returns a list of functions that can be uses to set or get the matrix and to set and get the cached matrix inverse
+## if X is passed as parameter, then the matrix is initialized with it, else an empty matrix is used
+## cacheSolve(x) returns the inverse of the matrix actually setted on x
+## if inverse cached, then just returns cached value, else calculates and caches the inverse first
+## x is the list of functions return by makeCacheMatrix
 
-## Write a short comment describing this function
 
+## params
+## -> (optional) x should be a squared and invertible matrix. Sets the actual matrix.
+##
+## returns a list of functions 
+## -> set(y): sets the matrix to y. Resets inverse cache.
+## -> get: returns the actual matrix
+## -> setinverse(inverse): caches the inverse of the matrix
+## -> getinverse: returns the cached matrix 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)
 }
 
 
-## Write a short comment describing this function
-
+## params
+## -> x is the list of functions returned by makeCacheMatrix
+## -> ... are arbitrary parameters that could be passed to "solve" function
+##
+## returns the inverse of the matrix. 
+## If inverse was already calculated, then it returns the cached copy, and prints a notice message "getting cached data"
 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
+}
\ No newline at end of file

From ed27278f57964fbb553c818f1d81e501a23ee7cf Mon Sep 17 00:00:00 2001
From: domangi <domenico.angilletta@gmail.com>
Date: Sat, 20 Dec 2014 14:52:30 +0100
Subject: [PATCH 2/2] added test code to comments

---
 cachematrix.R | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/cachematrix.R b/cachematrix.R
index a1cc04b3574..4c100ef83b1 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -3,6 +3,28 @@
 ## cacheSolve(x) returns the inverse of the matrix actually setted on x
 ## if inverse cached, then just returns cached value, else calculates and caches the inverse first
 ## x is the list of functions return by makeCacheMatrix
+##
+## Test Code
+## 1) create a 2x2 invertible matrix
+## > A <- matrix(c(1,2,2,3), 2, 2)
+##       [,1] [,2]
+## [1,]    1    2
+## [2,]    2    3
+##
+## 2) call makeCacheMatrix to get the special matrix
+## > X <- makeCacheMatrix(A)
+##
+## 3) call cacheSolve to get the inverse of the matrix
+## > inverse <- cacheSolve(X)
+##       [,1] [,2]
+## [1,]   -3    2
+## [2,]    2   -1
+##
+## 4) Test that the inverse is correct: A * inverse = I
+## > A %*% inverse
+##
+## 5) Call cacheSolve again should print the message "getting cached data"
+
 
 
 ## params
@@ -13,6 +35,9 @@
 ## -> get: returns the actual matrix
 ## -> setinverse(inverse): caches the inverse of the matrix
 ## -> getinverse: returns the cached matrix inverse
+##
+## example
+## > X <- makeCacheMatrix(matrix(c(1,2,2,3), 2, 2))
 makeCacheMatrix <- function(x = matrix()) {
         i <- NULL
         set <- function(y) {
@@ -34,6 +59,11 @@ makeCacheMatrix <- function(x = matrix()) {
 ##
 ## returns the inverse of the matrix. 
 ## If inverse was already calculated, then it returns the cached copy, and prints a notice message "getting cached data"
+##
+## example
+## > X <- makeCacheMatrix(matrix(c(1,2,2,3), 2, 2))
+## > inverse <- cacheSolve(X)
+## > matrix(c(1,2,2,3), 2, 2) %*% inverse # should return the 2x2 identity matrix
 cacheSolve <- function(x, ...) {
         ## Return a matrix that is the inverse of 'x'
         i <- x$getinverse()