From 79adc39667e2079107b7fac309de50a76ffd657b Mon Sep 17 00:00:00 2001
From: miktro <miktro314@gmail.com>
Date: Fri, 9 Jan 2015 15:32:21 +0000
Subject: [PATCH 1/2] Completed and tested the 2 functions
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Completed and tested the 2 functions.
Used system.time to compare speed of solve vs cacheSolve
on a 10x10 matrix.
cacheSolve was (only) 12 times faster¬!
---
 cachematrix.R | 50 +++++++++++++++++++++++++++++++++++---------------
 1 file changed, 35 insertions(+), 15 deletions(-)

diff --git a/cachematrix.R b/cachematrix.R
index a50be65aa4..2f13838e6e 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -1,15 +1,35 @@
-## Put comments here that give an overall description of what your
-## functions do
-
-## Write a short comment describing this function
-
-makeCacheMatrix <- function(x = matrix()) {
-
-}
-
-
-## Write a short comment describing this function
-
-cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
-}
+## Put comments here that give an overall description of what your
+## functions do
+
+## This creates a new object that stores a matrix 
+## together with it's inverse - initially set to NULL
+
+makeCacheMatrix <- function(x = matrix()) {
+    mi <- NULL
+    set <- function(y) {
+        x <<- y
+        mi <<- NULL
+    }
+    get <- function() x
+    setinverse <- function(inv) mi <<- inv
+    getinverse <- function() mi
+    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'
+    mi <- x$getinverse()
+    if(!is.null(mi)) {
+        #message("getting cached matrix inverse")
+        return(mi)
+    }
+    data <- x$get()
+    mi <- solve(data, ...)
+    x$setinverse(mi)
+    mi
+}

From 0582334e02bf9a6ad3bc8253b7688931cd0d465d Mon Sep 17 00:00:00 2001
From: miktro <miktro314@gmail.com>
Date: Fri, 9 Jan 2015 15:35:35 +0000
Subject: [PATCH 2/2] Added comment to cacheSolve

---
 cachematrix.R | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/cachematrix.R b/cachematrix.R
index 2f13838e6e..e91407d7fe 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -19,7 +19,9 @@ makeCacheMatrix <- function(x = matrix()) {
 }
 
 
-## Write a short comment describing this function
+## cacheSolve checks supplied object to see if it has an inverse already.
+## If there is an inverse then it is returned.
+## Otherwise the inverse is 'solve'd, stored for furture use and returned.
 
 cacheSolve <- function(x, ...) {
         ## Return a matrix that is the inverse of 'x'