From d9c2e140acd3231f6c1663fe05e547ef9f29b200 Mon Sep 17 00:00:00 2001
From: caldwellsa <caldwellsa@gmail.com>
Date: Wed, 23 Apr 2014 22:07:32 -0700
Subject: [PATCH] commit completed assignment

---
 cachematrix.R | 51 ++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 46 insertions(+), 5 deletions(-)

diff --git a/cachematrix.R b/cachematrix.R
index a50be65aa44..b17ab700c3d 100644
--- a/cachematrix.R
+++ b/cachematrix.R
@@ -1,15 +1,56 @@
-## Put comments here that give an overall description of what your
-## functions do
+## makeCacheMatrix is a function that creates an object that stores a 
+## matrix and corresponding inverted matrix and four functions to manage 
+## them.
 
-## Write a short comment describing this function
+## set(y) stores the matrix, and sets the inverse to NULL (since the
+##          old value is invalid and needs to be recalculated)
+## get() retrieves the matrix
+## setmatrix(xinv) stores the inverted matrix
+## getmatrix() retrieves the inverted matrix
 
 makeCacheMatrix <- function(x = matrix()) {
-
+    m <- NULL
+    set <- function(y) {
+        x <<- y
+        m <<-NULL
+    }
+    get <- function() x
+    setmatrix <- function(xinv) m <<- xinv
+    getmatrix <- function() m
+    list (set=set, get=get, setmatrix=setmatrix, getmatrix=getmatrix)
 }
 
+## cacheSolve checks if there is a cached value and returns the value if 
+##      available, otherwise recaculates the inverse and caches the new value
 
-## Write a short comment describing this function
 
 cacheSolve <- function(x, ...) {
         ## Return a matrix that is the inverse of 'x'
+    m <- x$getmatrix()
+    if (!is.null(m)) {
+        message("getting cached matrix...")
+        return(m)
+    }
+    xm <- x$get()           ## xm gets the non-inverted matrix
+    m <- solve(xm, ...)     ## m is the inverted matrix solution to be cached
+    x$setmatrix(m)
 }
+
+## usage example:
+# > obj <- makeCacheMatrix()
+# > obj$set(matrix(1:4,nrow=2,ncol=2))
+# > obj$get()
+# [,1] [,2]
+# [1,]    1    3
+# [2,]    2    4
+# > cacheSolve(obj)
+# > obj$getmatrix()
+# [,1] [,2]
+# [1,]   -2  1.5
+# [2,]    1 -0.5
+# > cacheSolve(obj)
+# getting cached matrix...
+# [,1] [,2]
+# [1,]   -2  1.5
+# [2,]    1 -0.5
+# >