rdpeng · Apr 26, 2015
Showing with 47 additions and 9 deletions.

+47 −9 cachematrix.R
diff --git a/cachematrix.R b/cachematrix.R
@@ -1,15 +1,53 @@
-## Put comments here that give an overall description of what your
-## functions do
-
-## Write a short comment describing this function
-
-makeCacheMatrix <- function(x = matrix()) {
+# makeCacheMatrix creates a list containing a function to
+# 1. set the value of the matrix
+# 2. get the value of the matrix
+# 3. set the value of inverse of the matrix
+# 4. get the value of inverse of the matrix
 
+makeCacheMatrix <- function(x = numeric()) {
+
+  # holds the cached value or NULL if nothing is cached
+  # initially nothing is cached so set it to NULL
+  cache <- NULL
+
+  # store a matrix
+  setMatrix <- function(newValue) {
+    x <<- newValue
+    # since the matrix is assigned a new value, flush the cache
+    cache <<- NULL
+  }
+
+  # returns the stored matrix
+  getMatrix <- function() {
+    x
+  }
+
+  # cache the given argument 
+  cacheInverse <- function(solve) {
+    cache <<- solve
+  }
+
+  # get the cached value
+  getInverse <- function() {
+    cache
+  }
+
+  # return a list. Each named element of the list is a function
+  list(setMatrix = setMatrix, getMatrix = getMatrix, cacheInverse = cacheInverse, getInverse = getInverse)
 }
 
 
-## Write a short comment describing this function
+## Calculate the inverse of the special "matrix" created with the above
+## function, reusing cached result if it is available
 
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
-}
+  i <- x$getinverse()
+  if(!is.null(i)) {
+    message("getting cached data")
+    return(i)
+  }
+  m <- x$get()
+  i <- solve(m, ...)
+  x$setinverse(i)
+  i
+}