Implement makeCacheMatrix and cacheSolve

jsanders · jsanders · commit d6db7bb9741d · 2014-05-21T18:16:04.000-06:00
diff --git a/cachematrix.R b/cachematrix.R
@@ -1,15 +1,34 @@
-## Put comments here that give an overall description of what your
-## functions do
+## Gives the inverse of a given matrix, caching the result
+## and using the cached result if available
 
-## Write a short comment describing this function
+## Builds an object that can store and retrieve a cached matrix inverse
 
 makeCacheMatrix <- function(x = matrix()) {
-
+  i <- NULL
+  set <- function(y) {
+    x <<- y
+    i <<- NULL
+  }
+  get <- function() x
+  setinv <- function(inv) i <<- inv
+  getinv <- function() i
+  list(set = set, get = get,
+       setinv = setinv,
+       getinv = getinv)
 }
 
 
-## Write a short comment describing this function
+## Returns the inverse of a special matrix
+## Uses cached value if available, calculates and caches if not
 
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+  i <- x$getinv()
+  if(!is.null(i)) {
+    message("getting cached data")
+    return(i)
+  }
+  data <- x$get()
+  i <- solve(data, ...)
+  x$setinv(i)
+  i
 }
