Complete the functions.

Author: linyiru

cachematrix.R

@@ -1,15 +1,35 @@
-## Put comments here that give an overall description of what your
-## functions do
-
-## Write a short comment describing this function
-
+## funtcion makeCacheMatrix() creates a special "matrix" object that can cache its inverse.
 makeCacheMatrix <- function(x = matrix()) {
-
+    m <- NULL
+    set <- function(y) {
+        x <<- y
+        m <<- NULL
+    }
+    get <- function() x
+    setInverse <- function(solve) m <<- solve
+    getInverse <- function() m
+    list(set = set, get = get,
+        setInverse = setInverse,
+        getInverse = getInverse)
 }
 
+## cacheSolve() computes the inverse of the special "matrix" returned by makeCacheMatrix above.
+## If the inverse has already been calculated (and the matrix has not changed), then the cachesolve
+## should retrieve the inverse from the cache.
+cacheSolve <- function(x, ...) {
+    m <- x$getInverse()
 
-## Write a short comment describing this function
+    ## Return a matrix that is the inverse of 'x' if the inverse has already been calculated and cached. 
+    if(!is.null(m)) {
+        message("getting cached data")
+        return(m)
+    }
 
-cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+    ## Calculate the inverse of 'x' if the cached data doesn't exist.
+    data <- x$get()
+    m <- solve(data, ...)
+    x$setInverse(m)
+
+    ## Return a matrix that is the inverse of 'x'
+    m
 }