From 8ca4a15c2d0296e25234c03bdc842a03875ea568 Mon Sep 17 00:00:00 2001
From: bjegithub <brian.j.engelhardt.79@gmail.com>
Date: Tue, 22 Apr 2014 19:49:19 -0400
Subject: [PATCH 1/2] First attempt at functions

---
 cachematrix.R | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/cachematrix.R b/cachematrix.R
index a50be65aa44..ed3e818c439 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -4,12 +4,31 @@
 ## Write a short comment describing this function
 
 makeCacheMatrix <- function(x = matrix()) {
-
+	inv <- NULL
+	set <- function(y) {
+		x <<- y
+		inv <<- NULL
+	}
+	get <- function() x
+	setinverse <- function(solve) inv <<- solve
+	getinverse <- function() inv
+	list(set = set, get = get, setinverse = setinverse, 
+		getinverse = getinverse )
 }
 
 
 ## Write a short comment describing this function
 
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+	## Return a matrix that is the inverse of 'x'
+
+	inv <- x$getinverse()
+	if(!is.null(inv)) {
+		message("getting cached data")
+		return(inv)
+	}
+	data <- x$get()
+	inv <- solve(data, ...)
+	x$setinv(inv)
+	inv
 }

From aad5ec97adc8750c40b6259edb4edb0e0b46644d Mon Sep 17 00:00:00 2001
From: bjegithub <brian.j.engelhardt.79@gmail.com>
Date: Tue, 22 Apr 2014 20:38:05 -0400
Subject: [PATCH 2/2] Final coding changes & added comments

---
 cachematrix.R | 60 ++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 48 insertions(+), 12 deletions(-)

diff --git a/cachematrix.R b/cachematrix.R
index ed3e818c439..2f44540df80 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -1,34 +1,70 @@
-## Put comments here that give an overall description of what your
-## functions do
+## Brian J. Engelhardt
+## R Programming Assignment #2
+## 04/22/2014
+##
+## This file contains two functions that allow the user to construct a "special" matrix that can
+## be solved using the cacheSolve() function, which will cache the time consuming inverse
+## calculations, so repeated calls to cacheSolve (for the same matrix data) will not result in
+## re-calculating the inverse of the matrix.
 
-## Write a short comment describing this function
+
+## makeCacheMatrix
+## Creates a special "matrix", which is really a list of 4 functions allowing access to the data
+##
+## Args:
+##	x : a matrix
+##
+## Returns:
+##	A list of 4 functions that allow you to get/set the matrix, and get/set the invere of the matrix
 
 makeCacheMatrix <- function(x = matrix()) {
 	inv <- NULL
+
+	## set the matrix data, and set the inverse to NULL, since the matrix data has changed
 	set <- function(y) {
 		x <<- y
 		inv <<- NULL
 	}
+
 	get <- function() x
-	setinverse <- function(solve) inv <<- solve
-	getinverse <- function() inv
-	list(set = set, get = get, setinverse = setinverse, 
-		getinverse = getinverse )
+
+	setInverse <- function(inverse) inv <<- inverse
+
+	getInverse <- function() inv
+
+	list(set = set, get = get, setInverse = setInverse, 
+		getInverse = getInverse )
 }
 
 
-## Write a short comment describing this function
+## cacheSolve
+## Calculate the inverse of a matrix, given a "special" matrix. If the inverse has already been
+## calculated, then the inverse is just retrieved from memory
+##
+## Args:
+##	x : a special matrix created from "makeCacheMatrix"
+##
+## Returns:
+##	The inverse of the matrix contained in the special matrix x.
 
 cacheSolve <- function(x, ...) {
-	## Return a matrix that is the inverse of 'x'
 
-	inv <- x$getinverse()
+	inv <- x$getInverse()
+
 	if(!is.null(inv)) {
-		message("getting cached data")
+		## The inverse has already been calculated, just return it
+		message("Retrieving cached inverse")
 		return(inv)
 	}
+
+	## in this case, the inverse has not been calculated, so retrieve the original
+	## matrix data from x, and then solve the inverse
 	data <- x$get()
 	inv <- solve(data, ...)
-	x$setinv(inv)
+
+	## store the inverse back in the "special" matrix x, so that if we need it again
+	## it doesn't have to be solved again
+	x$setInverse(inv)
+
 	inv
 }