Checking in code for programming assignment 2.

Author: John Kinsella

cachematrix.R

@@ -1,15 +1,56 @@
-## Put comments here that give an overall description of what your
-## functions do
-
-## Write a short comment describing this function
+## cachematrix - R functions to compute and cache inverse of a Matrix
+##
+## Written by John Kinsella for Coursera class "R Programming"
+##
 
+## Function representing a matrix object
+## capable of caching it's inverse value
+##
+## Usage:
+##   myMatrix <- makeCacheMatrix(x)
+## Arguments:
+##   x - matrix value to initially store
+## Returns:
+##   Returns a list of 4 functions related to the matrix:
+##   * set(newValue) - set new value for matrix
+##   * get() - get the current matrix value
+##   * setInverse(inverseMatrix) - set the inverse matrix value
+##   * getInverse() - get the inverse of current matrix if set, NULL otherwise
 makeCacheMatrix <- function(x = matrix()) {
+  inverseMatrix <- NULL
+
+  set <- function(newValue) {
+    x <<- newValue
+    inverseMatrix <<- NULL
+  }
+  get <- function() x
+  setinverse <- function(targetInverse) inverseMatrix <<- targetInverse
+  getinverse <- function() inverseMatrix
 
+  list(set=set, get=get, setinverse=setinverse, getinverse=getinverse)
 }
 
+## Computes inverse of matrix. If inverse was already calculated, returns cached
+## value.
+##
+## Usage:
+##   invertedMatrix <- cacheSolve(x)
+## Arguments:
+##   x - list generated by makeCacheMatrix()
+## Returns:
+##   inverted version of matrix in x.
+cacheSolve <- function(x, ...) {
+  inverseMatrix <- x$getinverse()
 
-## Write a short comment describing this function
+  # If matrix inverse has been calculated, returned cached value
+  if(!is.null(inverseMatrix)) {
+    message("Getting cached data")
+    return(inverseMatrix)
+  }
 
-cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+  # If not cached already, calculate inverse and return
+  data <- x$get()
+  inverseMatrix <- solve(data)
+  x$setinverse(inverseMatrix)
+  inverseMatrix
 }