text clarification

LICENSE

@@ -0,0 +1,13 @@
+Copyright (c) 2014, Grzegorz Oledzki
+
+Permission to use, copy, modify, and/or distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

README.md

@@ -20,7 +20,7 @@ current environment. Below are two functions that are used to create a
 special object that stores a numeric vector and caches its mean.
 
 The first function, `makeVector` creates a special "vector", which is
-really a list containing a function to
+really a list containing four functions to
 
 1.  set the value of the vector
 2.  get the value of the vector

cachematrix.R

@@ -1,15 +1,29 @@
-## Put comments here that give an overall description of what your
-## functions do
-
-## Write a short comment describing this function
+## A pair of functions that cache the inverse of a matrix, for the sake of saving time of 
+## re-calcuating the result on subsequent calls.
 
+## Creates a special wrapper around given matrix, 
+## which offers a quick (cached) computation of matrix inverse
 makeCacheMatrix <- function(x = matrix()) {
+   matrix <- x
+   inverse <- NULL
 
+   getCachedInverse <- function() inverse
+   calculateInverseAndStore <-function() {
+     inverse <<- solve(matrix)
+     inverse
+   }
+   list(getCachedInverse = getCachedInverse, calculateInverseAndStore = calculateInverseAndStore)
 }
 
 
-## Write a short comment describing this function
+## Returns inverse of a wrapped matrix created with makeCacheMatrix.
+## Ensures the matrix inverse is calculated only once and cached for subsequent calls.
+cacheSolve <- function(cacheMatrix, ...) {
+  candidate <- cacheMatrix$getCachedInverse()
+  if (!is.null(candidate)) {
+    message("from cache")
+    return (candidate)
+  }
 
-cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+  cacheMatrix$calculateInverseAndStore()
 }