update cachematrix script

geoph · geoph · commit eacd0e4c8dfd · 2014-05-22T19:51:02.000+03:00
diff --git a/cachematrix.R b/cachematrix.R
@@ -1,15 +1,36 @@
-## Put comments here that give an overall description of what your
-## functions do
 
-## Write a short comment describing this function
 
-makeCacheMatrix <- function(x = matrix()) {
+## It creates the special "matrix" and provides accesses
+## to retreive and set both the original matrix and its inverse.
+
 
+makeCacheMatrix <- function(x = matrix()) {
+  inverse <- NULL
+  set <- function(y) {   # set a new matrix
+    x <<- y
+    inverse <<- NULL     # When the matrix is set, the (cached) inverse is set to NULL
+  }
+  get <- function() x    # get matrix
+  setInverse <- function(inv) inverse <<- inv ##Inverse function
+  getInverse <- function() inverse
+  list(set = set, 
+       get = get, 
+       setInverse = setInverse, 
+       getInverse = getInverse)
 }
 
+## It calculates the inverse of the matrix provided by makeCacheMatrix
 
-## Write a short comment describing this function
 
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+  ## Return a matrix that is the inverse of 'x'
+  inv <- x$setInverse()                # get the cached inverse
+  if(!is.null(inv)) {                  # checks if the CacheMatrix has a cached inverse
+    message("getting cached inverse")
+    return(inv)                        # return the cached inverse and exit the function
+  }
+  mat <- x$get()                       # retrive the original matrix 
+  mat.inv <- solve(mat, ...)           # invert the original matrix
+  x$setInverse(mat.inv)                # put the inverse matrix calculated in the cache 
+  mat.inv                              # return the inverse of the input matrix
 }
