committing solution to assignment rdpeng#2

Author: pgoldweic

cachematrix.R

@@ -1,15 +1,39 @@
-## Put comments here that give an overall description of what your
-## functions do
+## These two functions work very similarly to how the example functions for this programming assignment
+## (that is, makeVector and cacheMean) work
 
-## Write a short comment describing this function
+## makeCacheMatrix creates a special "matrix" which is really a list containing functions to:
+## 1- set the value of the matrix
+## 2- get the value of the matrix
+## 3- set the value of the inverse
+## 4- get the value of the inverse
 
 makeCacheMatrix <- function(x = matrix()) {
-
+  i <- NULL
+  set <- function(y) {
+    x <<- y
+    i <<- NULL
+  }
+  get <- function() x
+  setinverse <- function(inv) i<<- inv
+  getinverse <- function() i
+  list(set= set, get = get, setinverse= setinverse, getinverse= getinverse)
 }
 
 
-## Write a short comment describing this function
+## cacheSolve calculates the inverse of a special "matrix" created with the above function.
+## It first checks to see if the inverse has already been calculated, and if so, returns the
+## inverse value from the cache and skips the computation. Otherwise, it calculates the inverse
+## of the matrix - using solve(x)- and sets the value of the cached inverse via the setinverse function.
 
 cacheSolve <- function(x, ...) {
         ## Return a matrix that is the inverse of 'x'
+  i <- x$getinverse()
+  if (!is.null(i)) {
+      message("getting cached data")
+    return(i)
+  }
+  data <- x$get()
+  i <- solve(data)
+  x$setinverse(i)
+  i
 }