diff --git a/cachematrix.R b/cachematrix.R
index a50be65aa44..e01fa7be1a3 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -1,15 +1,33 @@
-## Put comments here that give an overall description of what your
-## functions do
-
-## Write a short comment describing this function
+## cacheSolve works objects created with makeCacheMatrix to 
+## store previously computed results of matrix inverses
 
+## makeCacheMatrix sets up a matrix object via a list 
+## to store itself and a cache of its inverse
 makeCacheMatrix <- function(x = matrix()) {
-
+        mi <- NULL
+        set <- function(y) {
+                x <<- y
+                mi <<- NULL
+        }
+        get <- function() x
+        setmatrix_inv <- function(solvex) mi <<- solvex
+        getmatrix_inv <- function() mi
+        list(set = set, get = get,
+             setmatrix_inv = setmatrix_inv,
+             getmatrix_inv = getmatrix_inv)
 }
 
-
-## Write a short comment describing this function
-
+## cacheSolve first checks if the matrix's inverse has previously been 
+## computed and cached to be returned. Computes and cache the inverse otherwise.
 cacheSolve <- function(x, ...) {
         ## Return a matrix that is the inverse of 'x'
+        mi <- x$getmatrix_inv()
+        if(!is.null(mi)) {
+                message("getting cached data")
+                return(mi)
+        }
+        data <- x$get()
+        mi <- solve(data, ...)
+        x$setmatrix_inv(mi)
+        mi
 }