Completed both makeCacheMatrix and makeSolve functions

Author: yaowee

cachematrix.R

@@ -1,15 +1,58 @@
-## Put comments here that give an overall description of what your
-## functions do
+## makeCacheMatrix function creates a matrix object out of a matrix 'x' that
+## contains getters and setters functions for the value of the matrix and also
+## the inverse of the matrix.
+## cacheSolve is a function that takes the matrix object created by makeCacheMatrix
+## function and tries to calculate the inverse of the matrix object if the inverse 
+## of the object is not calculated before and cached.
 
-## Write a short comment describing this function
+## Creates an a matrix, x, which is the input argument. Function has methods 
+## that returns the inverse of matrix, x. The function contains is a list of 
+## functions: 
+## 1. set the matrix
+## 2. get the matrix
+## 3. set the inverse of the matrix
+## 4. get the inverse of the matrix
 
 makeCacheMatrix <- function(x = matrix()) {
-
+    ##variable that caches the inverse of matrix x
+    inv <- NULL
+    ## Set the matrix and resets the cached inverse matrix to NULL
+    set <- function(y = matrix()){
+        x <<- y
+        inv <<- NULL
+    }
+    ## Returns the matrix
+    get <- function() x
+    ## Sets the inverse of the matrix in variable inv
+    setinv <- function(solve) inv <<- solve
+    ## Gets the inverse of the matrix
+    getinv <-function() inv
+    ## List of functions in this function
+    list(set = set, get = get,
+         setinv = setinv,
+         getinv = getinv)
 }
 
 
-## Write a short comment describing this function
+## Functions returns the inverse of a matrix 'x' by first attempting to return 
+## any non-null inverse matrix value that is cached. If the inverse matrix value
+## is not cached, the inverse of matrix 'x' is calculated and cached before
+## the value of the inverse matrix is return.
 
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+    ## Gets the inverse from the matrix object
+    inv <- x$getinv()
+    ## if the inverse is cached, return the cached inverse matrix
+    if(!is.null(inv)){
+        message("getting cached data")
+        return(inv)
+    }
+    ## get the matrix data
+    data <- x$get()
+    ## Calculate the inverse of the matrix 'x'
+    inv <- solve(data, ...)
+    ## cache the inverse value of matrix 'x'
+    x$setinv(inv)
+    ## Return a matrix that is the inverse of 'x'
+    inv
 }