Complete assignment 2

Author: bryfox

cachematrix.R

@@ -1,15 +1,54 @@
-## Put comments here that give an overall description of what your
-## functions do
+# cachematrix.R
+# A suite of functions to cache time-consuming matrix inversion computations
+#
+# Defines a pseudo "matrix" class which manages the cache,
+# and a cacheSolve() function to compute the inverse.
+#
+# Example:
+# m1 <- makeCacheMatrix(matrix(rnorm(16), 4, 4))
+# cacheSolve(m1)
+#
+# Based on https://github.com/rdpeng/ProgrammingAssignment2/blob/master/cachematrix.R
 
-## Write a short comment describing this function
 
+# Returns a special "matrix" object (list) that can cache its inverse.
 makeCacheMatrix <- function(x = matrix()) {
+    cachedInverse <- NULL
 
+    # Accessors to the underlying matrix data
+    get <- function () x
+    set <- function (newMatrix) {
+        x             <<- newMatrix
+        cachedInverse <<- NULL
+    }
+
+    # Convenient way to call cacheSolve()
+    getInverse <- function () cacheSolve(obj)
+
+    getCachedInverse <- function () cachedInverse
+    setCachedInverse <- function (inverse) cachedInverse <<- inverse
+    obj <- list(get = get,
+         set = set,
+         getInverse = getInverse,
+         getCachedInverse = getCachedInverse,
+         setCachedInverse = setCachedInverse)
 }
 
 
-## Write a short comment describing this function
+# This function computes the inverse of the special "matrix"
+# returned by `makeCacheMatrix`.
+#
+# If the inverse has already been calculated (and the matrix has not changed),
+# then the cached result will be returned.
+#
+# Returns a matrix that is the inverse of 'x'
+cacheSolve <- function (x, ...) {
+    inverse <- x$getCachedInverse()
+
+    if (is.null(inverse)) {
+        inverse <- solve(x$get())
+        x$setCachedInverse(inverse)
+    }
 
-cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+    inverse
 }