diff --git a/cachematrix.R b/cachematrix.R
index a50be65aa44..1174ca5054b 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -1,15 +1,40 @@
 ## Put comments here that give an overall description of what your
 ## functions do
 
-## Write a short comment describing this function
-
+##  returns a list of functions to get/set an 'internal' matrix and get/set its inverse. 
+## (get, set, getinv, setinv).
+## If the matrix is 'set' via this list's set function, the inverse matrix will be cleared.
 makeCacheMatrix <- function(x = matrix()) {
+  m <- NULL
+  set <- function(y) {
+    x <<- y
+    m <<- NULL
+  }
+  get <- function() x
+  setinv <- function(matinv) m <<- matinv
+  getinv <- function() m
+  list(set = set, get = get,
+       setinv = setinv,
+       getinv = getinv)
 
 }
 
 
-## Write a short comment describing this function
-
+## Returns inverse of x, storing the computation of the inverse
+## x is not actually a matrix, but rather a list generated by makeCacheMatrix
+## This will set the 'internal' inverse matrix for mackCacheMatrix context if
+## it doesn't already exist, and will simply return that matrix if it exists w/o
+## recomputing.
 cacheSolve <- function(x, ...) {
+  
+  m <- x$getinv()
+  if(!is.null(m)) {
+    message("getting cached data")
+    return(m)
+  }
+  data <- x$get()
+  m <- solve(data)
+  x$setinv(m)
+  m
         ## Return a matrix that is the inverse of 'x'
 }
diff --git a/test.R b/test.R
new file mode 100644
index 00000000000..8c1d7442748
--- /dev/null
+++ b/test.R
@@ -0,0 +1,11 @@
+source('./cachematrix.R')
+x <- matrix(c(2,2,3,2),  nrow=2, ncol=2)
+y <- matrix(c(1, -1, 1, 2),  nrow=2, ncol=2)
+cmx <- makeCacheMatrix(x)
+cmy <- makeCacheMatrix(y)
+invx <- cacheSolve(cmx)
+invy <- cacheSolve(cmy)
+solve(cacheSolve(cmy))
+solve(cacheSolve(cmx))
+solve(cacheSolve(cmy))
+solve(cacheSolve(cmx))