Completes assignment 2

sabrams · sabrams · commit dd8abd394714 · 2016-02-21T21:42:54.000-05:00
diff --git a/cachematrix.R b/cachematrix.R
@@ -1,15 +1,37 @@
 ## Put comments here that give an overall description of what your
 ## functions do
 
-## Write a short comment describing this function
-
+##  returns a list of functions to get/set an 'internal' matrix and get/set its inverse. 
+## (get, set, getinv, setinv).
+## If the matrix is 'set' via this list's set function, the inverse matrix will be cleared.
 makeCacheMatrix <- function(x = matrix()) {
+  m <- NULL
+  set <- function(y) {
+    x <<- y
+    m <<- NULL
+  }
+  get <- function() x
+  setinv <- function(matinv) m <<- matinv
+  getinv <- function() m
+  list(set = set, get = get,
+       setinv = setinv,
+       getinv = getinv)
 
 }
 
 
-## Write a short comment describing this function
-
+## Returns inverse of x, storing the computation of the inverse
+## x is not actually a matrix, but rather a list generated by makeCacheMatrix
 cacheSolve <- function(x, ...) {
+  
+  m <- x$getinv()
+  if(!is.null(m)) {
+    message("getting cached data")
+    return(m)
+  }
+  data <- x$get()
+  m <- matrix(rev(c(data)), nrow=nrow(data), ncol=ncol(data))
+  x$setinv(m)
+  m
         ## Return a matrix that is the inverse of 'x'
 }
