From 52a82a67de78fe1f99d4db1148456d4af96ecdb2 Mon Sep 17 00:00:00 2001
From: Hiep Khuu <hkdev@outlook.com>
Date: Sat, 23 Aug 2014 15:54:28 -0700
Subject: [PATCH 1/3] Added makeCacheMatrix() and cacheSolve() functions to
 find inverse of an invertible matrix input

---
 cachematrix.R | 57 +++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 51 insertions(+), 6 deletions(-)

diff --git a/cachematrix.R b/cachematrix.R
index a50be65aa44..2081b3339fd 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -1,15 +1,60 @@
-## Put comments here that give an overall description of what your
-## functions do
+## The following functions below will help find the inverse of a matrix, if it is
+## invertible, given a matrix object. 
+## A matrix object can be created using makeCacheMatrix() function. The created
+## matrix object has capability to store both the matrix input and matrix inverse result.
+## In addition, if the matrix object already had the cached inverse result, the cacheSolve()
+## function will just return it without spending expensive resource to re-compute it.
 
-## Write a short comment describing this function
 
-makeCacheMatrix <- function(x = matrix()) {
+## This function creates a special "matrix" object that can cache its inverse
 
+makeCacheMatrix <- function(x = matrix()) {
+  invMatrix <- NULL
+  
+  ## Define a set() function to store matrix input data
+  set <- function(y){
+    x <<- y
+    invMatrix <<- NULL
+  }
+  
+  ## Define a get() function to return matrix input data
+  get <- function() x
+  
+  ## Define a getInverse() function to return the cached
+  ## matrix inverse result, if available
+  getInverse <- function() invMatrix
+  
+  ## Define a setInverse() function to store cached result
+  ## of inverse matrix of X
+  setInverse <- function(invX){
+    invMatrix <<- invX
+  }
+  
+  ## Define list of functions to be accessible
+  list(get = get, set = set, 
+       getInverse = getInverse, setInverse = setInverse)
+  
 }
 
 
-## Write a short comment describing this function
+## 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 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'
+  invMatrix <- x$getInverse()
+  
+  if (!is.null(invMatrix)){
+    message("Getting cached matrix inverse result")
+    return(invMatrix)
+  }
+  
+  ## Compute the matrix Inverse of X, assuming X is invertible
+  invMatrix <- solve(x$get())
+  
+  ## Cache the inverse matrix of X for next retrieval
+  x$setInverse(invMatrix)
+  
+  invMatrix
 }

From 821b85f933ef39762bc97f4445ecde0f1583699c Mon Sep 17 00:00:00 2001
From: Hiep Khuu <hkdev@outlook.com>
Date: Sat, 23 Aug 2014 16:22:08 -0700
Subject: [PATCH 2/3] Clean up comments

---
 cachematrix.R | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cachematrix.R b/cachematrix.R
index 2081b3339fd..712ae51e119 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -5,7 +5,6 @@
 ## In addition, if the matrix object already had the cached inverse result, the cacheSolve()
 ## function will just return it without spending expensive resource to re-compute it.
 
-
 ## This function creates a special "matrix" object that can cache its inverse
 
 makeCacheMatrix <- function(x = matrix()) {
@@ -56,5 +55,6 @@ cacheSolve <- function(x, ...) {
   ## Cache the inverse matrix of X for next retrieval
   x$setInverse(invMatrix)
   
+  ## Display the inverse matrix on console output
   invMatrix
 }

From 420d9188ec342acb67157c255a9ec5b035475367 Mon Sep 17 00:00:00 2001
From: Hiep Khuu <hkdev@outlook.com>
Date: Sat, 23 Aug 2014 16:23:03 -0700
Subject: [PATCH 3/3] Clean up comments

---
 cachematrix.R | 1 -
 1 file changed, 1 deletion(-)

diff --git a/cachematrix.R b/cachematrix.R
index 712ae51e119..c8629ab1cd8 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -55,6 +55,5 @@ cacheSolve <- function(x, ...) {
   ## Cache the inverse matrix of X for next retrieval
   x$setInverse(invMatrix)
   
-  ## Display the inverse matrix on console output
   invMatrix
 }