Update cachematrix.R

cachematrix.R

@@ -1,15 +1,27 @@
-## Put comments here that give an overall description of what your
-## functions do
+## makeCacheMatrix is a function that can cashe the inverse of a matrix.
+## If the inverse has already been calculated (and the matrix has not changed), then the cacheSolve function retrieves the inverse from the cache.
 
-## Write a short comment describing this function
+## This function creates a special "matrix" object that can cache its inverse
 
 makeCacheMatrix <- function(x = matrix()) {
-
+  inv <- NULL
+  get <- function() x
+  getinv <- function() inv <<- solve(x)
+  list(get = get,
+       getinv = getinv)
 }
 
 
-## Write a short comment describing this function
+## This function computes the inverse of the special "matrix" returned by makeCacheMatrix above. 
 
 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, ...)
+  inv
 }