diff --git a/cachematrix.R b/cachematrix.R
index a50be65aa44..ff50005fa0e 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -1,15 +1,36 @@
-## Put comments here that give an overall description of what your
-## functions do
+## a pair of functions that cache the inverse of a matrix 
 
-## Write a short comment describing this function
+## creates a special "matrix" object that can cache its inverse
 
 makeCacheMatrix <- function(x = matrix()) {
+    i <- NULL
+    set <- function(y){
+        x <<- y
+        i <<- NULL
+    }
+    get <- function() x
+    setinverse <- function(inverse) i <<- inverse
+    getinverse <- function() i
+    list(set = set, get = get,
+        setinverse = setinverse,
+        getinverse = getinverse)
 
 }
 
 
-## Write a short comment describing this function
+## computes the inverse of the special "matrix" returned by makeCacheMatrix 
+## above. If the inverse has already been calculated (and the matrix has not 
+## changed), then the cachesolve should retrieve the inverse from the cache 
 
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+    ## Return a matrix that is the inverse of 'x'
+    i <- x$getinverse()
+    if(!is.null(i)){
+        message("getting cached data")
+        return(i)
+    }
+    data <- x$get()
+    i <- solve(data,...)
+    x$setinverse(i)
+    i
 }