Add implementation to stub

Author: marcora

cachematrix.R

@@ -4,12 +4,31 @@
 ## Write a short comment describing this function
 
 makeCacheMatrix <- function(x = matrix()) {
-
+  inv <- NULL
+  set <- function(y) {
+    x <<- y
+    inv <<- NULL
+  }
+  get <- function() x
+  setinv <- function(val) inv <<- val
+  getinv <- function() inv
+  list(set = set,
+       get = get,
+       setinv = setinv,
+       getinv = getinv)
 }
 
 
-## Write a short comment describing this function
+## Return a matrix that is the inverse of 'x'
 
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+  inv <- x$getinv()
+  if(!is.null(inv)) {
+    message("getting cached data")
+    return(inv)
+  }
+  data <- x$get()
+  inv <- solve(data, ...)
+  x$setinv(inv)
+  inv
 }