cache matrix implementation

Author: dminikitin

cachematrix.R

@@ -1,15 +1,47 @@
-## Put comments here that give an overall description of what your
-## functions do
-
-## Write a short comment describing this function
-
-makeCacheMatrix <- function(x = matrix()) {
+## Note: names of the methods changed to follow guidlines suggested here:
+## https://google-styleguide.googlecode.com/svn/trunk/Rguide.xml#identifiers
 
+## factory function to create a matrix that can cache the value of its inverse
+MakeCacheMatrix <- function(x = matrix()) {
+  # initialize the cached value of matrix inverse to be NULL
+  inverse.cache <- NULL
+  
+  # create setter function to...
+  Set <- function(y) {
+    # ...store the matrix
+    x <<- y
+    # ...and reset the cached inverse value
+    inverse.cache <<- NULL
+  }
+  
+  # create getter function - return incapsulated matrix
+  Get <- function() x
+  
+  SetInverse <- function(inverse) inverse.cache <<- inverse
+  
+  GetInverse <- function() inverse.cache
+  
+  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'
+## Calculate the inverse of the matrix; get the cached inverse matrix if it exists 
+CacheSolve <- function(x, ...) {
+  # get cached inverse
+  inverse <- x$GetInverse()
+  # ...return cached inverse if it exists
+  if(!is.null(inverse)) {
+    message("getting cached data")
+    return(inverse)
+  }
+  # otherwise get the matrix
+  data <- x$Get()
+  # ...calculate inverse
+  inverse <- solve(data, ...)
+  # ...and cache it
+  x$SetInverse(inverse)
+  # return calculated inverse matrix object
+  inverse
 }

cachematrix.test.R

@@ -0,0 +1,16 @@
+source('cachematrix.R')
+
+# create square invertable marix
+m=rbind(c(1, -1/4), c(-1/4, 1))
+
+# create cached matrix
+cache.m <- MakeCacheMatrix(c)
+
+# caclulate inverse
+inv <- CacheSolve(cc)
+
+#print result
+inv
+
+# check the result of multiplication of inverse by original - expect identity matri
+inv %*% m