diff --git a/cachematrix.R b/cachematrix.R
index a50be65aa44..caabfae433b 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -1,15 +1,35 @@
-## Put comments here that give an overall description of what your
-## functions do
-
-## Write a short comment describing this function
-
+## Caches an matrix that is expensive to compute (memoization)
+## the Object has the following 4 methods
+## get() gets the matrix
+## set(m) sets a matrix m. This operation clears any previously cached matrix
+## getinv() gets the cached inversed matrix
+## setinv(m) sets (caches) the inversed matrix m 
 makeCacheMatrix <- function(x = matrix()) {
-
+  m <- NULL
+  set <- function(y) {
+    x <<- y
+    m <<- NULL
+  }
+  get <- function() x
+  setinv <- function(inv) m <<- inv
+  getinv <- function() m
+  list(set = set, get = get,
+       setinv = setinv,
+       getinv = getinv)
 }
 
-
-## Write a short comment describing this function
-
+## Calculates the inverse of a matrix and caches the result. Receives the same
+## parameters as the internal function solve(). Run ?solve for more information
+##
+## Returns an errror if the matrix cannot be inverted (https://en.wikipedia.org/wiki/Invertible_matrix)
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+  m <- x$getinv()
+  if(!is.null(m)) {
+    message("getting cached data")
+    return(m)
+  }
+  data <- x$get()
+  m <- solve(data, ...)
+  x$setinv(m)
+  m  
 }