coded functions for a cached inverse for a matrix

Author: pvhoffman

cachematrix.R

@@ -1,15 +1,43 @@
 ## Put comments here that give an overall description of what your
 ## functions do
 
+
 ## Write a short comment describing this function
+# makeCacheMatrix create an R object which calculates the matrix^-1 only once
 
 makeCacheMatrix <- function(x = matrix()) {
-
+   ix  <- NULL
+   set <- function(mx) {
+        x <<-  mx
+        ix <<- NULL
+   }
+   get <- function(){
+        x
+   }
+   setinverse <- function(inverse) {
+        ix <<- inverse
+   }
+   getinverse <- function() {
+        ix
+   }
+   list(set = set
+        , get = get
+        , setinverse = setinverse
+        , getinverse = getinverse)
 }
 
 
-## Write a short comment describing this function
-
+# returns the inverse matrix from the object obtained from 
+# makeCacheMatrix calculating the value only once
 cacheSolve <- function(x, ...) {
         ## Return a matrix that is the inverse of 'x'
+        i <- x$getinverse()
+        if(!is.null(i)){
+                return(i)
+        }
+        mx <- x$get()
+        i  <- solve(mx, ...)
+        x$setinverse(i)
+        i
 }
+