added makeCacheMatrix and cacheSolve

Author: patrickash

.gitignore

@@ -0,0 +1,4 @@
+.Rproj.user
+.Rhistory
+.RData
+ProgrammingAssignment2.Rproj

cachematrix.R

@@ -1,15 +1,35 @@
-## Put comments here that give an overall description of what your
-## functions do
+## The following functions allow you to create a matrix and cache the inverse of a 
+## matrix for later reference if it is available
 
-## Write a short comment describing this function
+## makeCacheMatrix: This function creates a special "matrix" object that can cache its inverse.
 
 makeCacheMatrix <- function(x = matrix()) {
-
+    inv <- NULL
+    set <- function( y ) {
+        x <<- y
+        inv <<- NULL
+    }
+    get <- function() x
+    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: This function 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, ...) {
-        ## Return a matrix that is the inverse of 'x'
+    ## Return a matrix that is the inverse of 'x'
+    inv <- x$getinverse()
+    if (!is.null(inv)) {
+        message("getting cached data")
+        return(inv)
+    }
+    message('still null')
+    data <- x$get()
+    inv <- solve(data)
+    x$setinverse(inv)
+    inv
 }