From 4cc0b5433005fbfc9ed75f6b297f582114197c89 Mon Sep 17 00:00:00 2001
From: demgenman <demgenman@outlook.com>
Date: Tue, 22 Apr 2014 20:52:56 +0200
Subject: [PATCH] Added function bodies for makeCacheMatrix and cacheSolve
 functions.

---
 cachematrix.R | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 56 insertions(+), 1 deletion(-)

diff --git a/cachematrix.R b/cachematrix.R
index a50be65aa44..2369f43b7ba 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -1,15 +1,70 @@
 ## Put comments here that give an overall description of what your
 ## functions do
+# makeCacheMatrix() creates and initualizes a "class object" "cachematrix" which contains
+# the original matrix, a cache for its inverse matrix, and a set of functions to manipulate
+# the original and inverse matrices.
+# cacheSolve() returns the inverse of the matrix of "class" cachematrix.
+# It stores the computed inverse in cache. If cacheSolve is called again for the same
+# source matrix, the inverse matrix is retrieved from cache.
 
 ## Write a short comment describing this function
+# Description: makeCacheMatrix creates and initualizes a "class object" "cachematrix". 
+# A cachematrix object has:
+# Functions set and get = Assign and get the (source) matrix data.
+# Variable matrix.cache = Matrix cache for holding an already calculated (inverse) matrix.
+# Functions setinverse and getinverse = Assign and get the (inverse) matrix stored in matrix.cache.
+# Arguments: matrix
 
 makeCacheMatrix <- function(x = matrix()) {
-
+    matrix.cache <- NULL
+    # Set original matrix data and invalidate cached inverse
+    set <- function(y) {
+        x <<- y
+        matrix.cache <<- NULL
+    }
+    # Get original matrix data
+    get <- function() {
+        x
+    }
+    # Store inverse matrix data in cache
+    setinverse <- function(s) {
+        matrix.cache <<- s
+    }
+    # Get inverse matrix data from cache
+    getinverse <- function() {
+        matrix.cache
+    }
+    # Return the cachematrix object
+    list(set = set, get = get,
+         setinverse = setinverse,
+         getinverse = getinverse)
 }
 
 
 ## Write a short comment describing this function
+# Description: cacheSolve returns the inverse of the matrix of "class" cachematrix.
+# Arguments: x = cachematrix
 
 cacheSolve <- function(x, ...) {
         ## Return a matrix that is the inverse of 'x'
+    # Retrieve  a possibly previously calculated matrix inverse from the cache
+    inverted.matrix <- x$getinverse()
+    # If NULL, cache was empty and inverse must be calculated first.
+    # Otherwise, return the cached inverse matrix.
+    if(!is.null(inverted.matrix)) {
+        message("getting cached data")
+        # Return the inverse matrix (from cache)
+        inverted.matrix
+    }
+    else {
+        message("calculating inverse and storing it in cache")
+        # Get original matrix values
+        original.matrix <- x$get()
+        # Solve to obtain inverse matrix
+        inverted.matrix <- solve(original.matrix , ...)
+        # Store inverse matrix into object's cache
+        x$setinverse(inverted.matrix)
+        # Return the inverse matrix (calculated)
+        inverted.matrix
+    }
 }