Update cachematrix.R

cachematrix.R

@@ -1,15 +1,50 @@
-## Put comments here that give an overall description of what your
-## functions do
 
-## Write a short comment describing this function
+## The aim of the folowing functions is to cache the
+## inverse matrix calculation so that we can avoid
+## multiple useless computations
 
-makeCacheMatrix <- function(x = matrix()) {
+## This function create a matrix that can have its 
+## inverse cached
 
+makeCacheMatrix <- function(x = matrix()) {
+
+      ## initialise the inverse matrix
+      inverse <- NULL
+
+      ## define the getter and setter functions
+      get <- function() x
+      set <- function(y) {
+            x <<- y
+            inverse <<- NULL
+      }
+
+      ## define the functions for the inverse
+      setInverse <- function(Inv) inverse <<- Inv
+      getInverse <- function() inverse
+
+      list(set = set, get = get,
+           setInverse = setInverse,
+           getInverse = getInverse)
 }
 
 
-## Write a short comment describing this function
+## This function returns the inverse of a matrix by first checking
+## if it has not been computed before !
 
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+
+      ## initialise the inverse matrix
+      inverse <- x$getInverse()
+
+      ## check the existence of a cached value
+      if(!is.null(inverse)) {
+            message("getting cached data")
+            return(inverse)
+      }
+      else {
+            data <- x$get()
+            inverse <- solve(data)
+            x$setInverse(inverse)
+            return(inverse)
+      }
 }