From a6ca2c430a68601e7993616a86bc8c5ad4a7ec65 Mon Sep 17 00:00:00 2001
From: attarwala <murtuza_attarwala@yahoo.com>
Date: Sun, 20 Apr 2014 01:21:24 -0700
Subject: [PATCH] Commit the changes for assignment2
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Create special matrix object that is capable of caching it’s inverse
once it is computed.
---
 cachematrix.R | 41 +++++++++++++++++++++++++++++++++++------
 1 file changed, 35 insertions(+), 6 deletions(-)

diff --git a/cachematrix.R b/cachematrix.R
index a50be65aa44..dfdc204b80f 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -1,15 +1,44 @@
-## Put comments here that give an overall description of what your
-## functions do
+## The functions here illustrate the use of <<- operator, and lexical scoping
+## in general. The idea of lexical scoping is that the function comes together
+## with its environment, also referred to as function closure.
 
-## Write a short comment describing this function
+## The makeCacheMatrix function creates a special matrix, which has a set of functions
+## to set and get the value of the matrix, and to get and set the inverse of that
+## matrix. cacheSolve calculates the inverse for this special matrix object, and
+## caches the result. Once the result is cached, it returns the cached result till
+## the underlying matrix object remains the same. It recomputes and recaches the
+## result if the underlying matrix object changes.
 
-makeCacheMatrix <- function(x = matrix()) {
+## Create a special matrix object that is capable of caching it's inverse
 
+makeCacheMatrix <- function(x = matrix()) {
+    matrixInverse <- NULL
+    set <- function(y) {
+        x <<- y
+        matrixInverse <<- NULL
+    }
+    get <- function() x
+    setinverse <- function(inverse) matrixInverse <<- inverse
+    getinverse <- function() matrixInverse
+    list(set = set, get = get, setinverse = setinverse, getinverse = getinverse)
 }
 
 
-## Write a short comment describing this function
+## Return the cached inverse for the special matrix object, if the matrix
+## has not changed, and the inverse for that already exists, compute otherwise and
+## update the cache.
 
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+    ## Return a matrix that is the inverse of 'x'
+    ## For this assignment we can assume that matrix 'x' is always
+    ## invertible, so no need to put any checks for that
+    inv <- x$getinverse()
+    if (!is.null(inv)) {
+        message("getting cached data")
+        return(inv)
+    }
+    data <- x$get()
+    inv <- solve(data, ...)
+    x$setinverse(inv)
+    inv
 }