diff --git a/.gitignore b/.gitignore
new file mode 100644
index 00000000000..d4b2867f2bf
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+.Rapp.history
diff --git a/cachematrix.R b/cachematrix.R
index a50be65aa44..f6e8613bce7 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -1,15 +1,55 @@
-## Put comments here that give an overall description of what your
-## functions do
+## calculates a special 'matrix', represented by a list containing
+## the following four functions to:
+##   1) set the value of the matrix
+##   2) get the value of the matrix
+##   3) set the inverse of the matrix (i.e. cache the inverse)
+##   4) get the (cached) inverse of the matrix
+makeCacheMatrix <- function(x = matrix()) {
+	
+	# private storage of inverse, initially set to NULL
+	# ... as inverse has not yet been calculcated
+	inverse <- NULL
+	
+	# function allowing value of matrix to be reassigned.
+	# we reset inverse to NULL as inverse will need to be
+	# recalculated for new matrix
+	set <- function(y) {
+		x <<- y
+		inverse <<- NULL
+	}
 
-## Write a short comment describing this function
+	# getter method - retrieve current matrix
+	get <- function() x
 
-makeCacheMatrix <- function(x = matrix()) {
+	# setter to cache inverse after calculation
+	setinverse <- function(inv) inverse <<- inv
 
+	# getter for pre-caculated inverse (may be null)
+	getinverse <- function() inverse
+	
+	# return list of 4 functions defined above
+	list(set = set, get = get, 
+		setinverse = setinverse, 
+		getinverse = getinverse)
 }
 
 
-## Write a short comment describing this function
-
+## Return a matrix that is the inverse of 'x'
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+	# retrieve cached inverse of x (may be null)  
+	m <- x$getinverse()
+
+	# if cached value is not null, use it, and print msg
+	if(!is.null(m)) {
+		message("getting cached data")
+		return(m)
+	}
+
+	# otherwise,retrieve matrix value, compute and store inverse
+	data <- x$get()
+	m <- solve(data, ...)
+	x$setinverse(m)
+
+	# return newly computed inverse
+	m
 }