From a66c8542a0b376a67ebb06970d80a89ad8830ba0 Mon Sep 17 00:00:00 2001
From: entmoot <w@y.com>
Date: Sat, 12 Apr 2014 20:39:05 +0200
Subject: [PATCH 1/2] solution

---
 cachematrix.R | 37 ++++++++++++++++++++++++++++++++-----
 1 file changed, 32 insertions(+), 5 deletions(-)

diff --git a/cachematrix.R b/cachematrix.R
index a50be65aa44..88ce27cb629 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -1,15 +1,42 @@
-## Put comments here that give an overall description of what your
-## functions do
+## Functions for cached matrix inverse operation
 
-## Write a short comment describing this function
 
-makeCacheMatrix <- function(x = matrix()) {
+## makeCacheMatrix creates special form of matrix that
+## enables caching of matrix inverse calculations
 
+makeCacheMatrix <- function(x = matrix()) {
+  inv<-NULL
+  set <- function(y) {
+    x <<- y
+    inv <<- NULL
+  }
+  get <- function() x
+  setinv <- function(inverse) inv <<- inverse
+  getinv <- function() inv
+  list(set = set, get = get,
+       setinv = setinv,
+       getinv = getinv)
 }
 
 
-## Write a short comment describing this function
+## cacheSolve uses special matrix object x created by makeCachedMatrix
+## in order to calculate the inverse of the matrix x.
+## When the matrix inversion result from previous calculation 
+## is available in the cache, it is just reported back 
+## without the new recalculation. Otherwise, the inverse is 
+## calculated and stored in the cache for future reuse
 
 cacheSolve <- function(x, ...) {
         ## Return a matrix that is the inverse of 'x'
+  inv <- x$getinv()
+  if(!is.null(inv)) {
+    message("getting cached data")
+    return(inv)
+  }
+  data <- x$get()
+  inv <- solve(data, ...)
+  x$setinv(inv)
+  inv
 }
+
+

From ef0b9b0131f534e536977e32b4d100e4a0a63117 Mon Sep 17 00:00:00 2001
From: entmoot <w@y.com>
Date: Fri, 25 Apr 2014 17:40:58 +0200
Subject: [PATCH 2/2] improvements

---
 cachematrix.R | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/cachematrix.R b/cachematrix.R
index 88ce27cb629..94fe7f10152 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -1,5 +1,16 @@
 ## Functions for cached matrix inverse operation
 
+## makeCacheMatrix is used for creation of special 
+## matrix object that caches the calculated inverse
+## until the matrix itself changes. 
+## cacheSolve uses special matrix object x created by 
+## makeCachedMatrix in order to calculate the inverse 
+## of the matrix x. When the matrix inversion result 
+## from previous calculation is available in the cache,
+## it is just reported back without the new recalculation. 
+## Otherwise, the inverse is calculated and stored in
+## the cache for future reuse
+
 
 ## makeCacheMatrix creates special form of matrix that
 ## enables caching of matrix inverse calculations
@@ -7,8 +18,11 @@
 makeCacheMatrix <- function(x = matrix()) {
   inv<-NULL
   set <- function(y) {
-    x <<- y
-    inv <<- NULL
+    if (!identical(x,y))
+    {
+        x <<- y
+        inv <<- NULL
+    }
   }
   get <- function() x
   setinv <- function(inverse) inv <<- inverse
@@ -19,12 +33,9 @@ makeCacheMatrix <- function(x = matrix()) {
 }
 
 
-## cacheSolve uses special matrix object x created by makeCachedMatrix
-## in order to calculate the inverse of the matrix x.
-## When the matrix inversion result from previous calculation 
-## is available in the cache, it is just reported back 
-## without the new recalculation. Otherwise, the inverse is 
-## calculated and stored in the cache for future reuse
+## cacheSolve takes special form of matrix as input
+## and returns its inverse, either by reporting the cached 
+## or calculated version
 
 cacheSolve <- function(x, ...) {
         ## Return a matrix that is the inverse of 'x'