rdpeng · Aug 23, 2014
Showing with 41 additions and 7 deletions.

+41 −7 cachematrix.R
diff --git a/cachematrix.R b/cachematrix.R
@@ -1,15 +1,49 @@
-## Put comments here that give an overall description of what your
-## functions do
+## The goal of this pair of functions is to cache the inverse of a matrix.
 
-## Write a short comment describing this function
 
-makeCacheMatrix <- function(x = matrix()) {
 
+## makeVector creates a special "matrix", which is really a matrix containing a function to
+## set the value of the squared matrix
+## get the value of the squared matrix
+## set the value of the inverse of the matrix
+## get the value of the inverse of the matrix
+
+makeCacheMatrix <- function(m = matrix()) {
+    inv <- NULL
+    set <- function(y) {
+        m <<- y
+        inv <<- NULL
+    }
+    get <- function() m
+    setinverse <- function(inverse) inv <<- inverse
+    getinverse <- function() inv
+
+    list(set = set, get = get,
+         setinverse = setinverse,
+         getinverse = getinverse)
 }
 
 
-## Write a short comment describing this function
+## cacheSolve function calculates the inverse of the matrix created with the makeCacheMatrix function. 
+## However, it first checks to see if the inverse of the matrix has already been calculated. 
+## If so, it gets the inverse of the matrix from the cache and skips the computation. 
+## Otherwise, it calculates the inverse of the matrix and sets the value of the inverse in the cache via the setinverse function.
 
-cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+cacheSolve <- function(m) {
+    ## Return a matrix that is the inverse of 'm'
+    inv <- m$getinverse()
+    if(!is.null(inv)) {
+        message("getting cached data")
+        return(inv)
+    }
+    data <- m$get()
+    inv <- solve(data)
+    m$setinverse(inv)
+    inv
+
 }
+
+
+## This code is used just for test purpose
+## m <- makeCacheMatrix(matrix(1:4,2,2))
+## t <- cacheSolve(m)