diff --git a/cachematrix.R b/cachematrix.R
index a50be65aa44..47c9cd5ccaf 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -1,15 +1,37 @@
 ## Put comments here that give an overall description of what your
 ## functions do
 
-## Write a short comment describing this function
+## makeCacheMatrix creates a structure to store the matrix, compute the inverse,
+## and retrieve the cached inverse.
 
 makeCacheMatrix <- function(x = matrix()) {
-
+  inv <- NULL
+  set <- function(y) {
+    x <<- y
+    inv <<- NULL
+  }
+  get <- function() x
+  setinv <- function(solve) inv <<- solve
+  getinv <- function() inv
+  list(set = set, get = get,
+       setinv = setinv,
+       getinv = getinv)
 }
 
 
-## Write a short comment describing this function
+## cacheSolve takes the output object of makeCacheMatrix as an input. If the inverse
+## has already been cached, it will be returned (with a message). If not, it will compute,
+## cache and return it.
 
 cacheSolve <- function(x, ...) {
         ## Return a matrix that is the inverse of 'x'
-}
+  inv <- x$getinv()
+  if(!is.null(inv)) {
+    message("getting cached data")
+    return(inv)
+  }
+  data <- x$get()
+  inv <- solve(data, ...)
+  x$setinv(inv)
+  inv
+}
\ No newline at end of file