Add matrix caching/solving functions.

David J. Weller-Fahy · David J. Weller-Fahy · commit afdec19aedeb · 2015-12-27T21:34:11.000-05:00
diff --git a/cachematrix.R b/cachematrix.R
@@ -1,15 +1,31 @@
-## Put comments here that give an overall description of what your
-## functions do
-
-## Write a short comment describing this function
+## Create method of storing matrices and calculating their inversions that only
+## calculates the inversion for a given matrix once.
 
+## Cached matrix data type (functions to store/retrieve matrix/inversion).
 makeCacheMatrix <- function(x = matrix()) {
-
+  m = NULL
+  set <- function(y) {
+    x <<- y
+    m <<- NULL
+  }
+  get <- function() x
+  setinverse <- function(inverse) m <<- inverse
+  getinverse <- function() m
+  list(set = set, get = get,
+       setinverse = setinverse,
+       getinverse = getinverse)
 }
 
-
-## Write a short comment describing this function
-
-cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+## Calculate inversion of matrix stored in cached matrix data type if needed.
+cacheSolve <- function(x) {
+  ## Return a matrix that is the inverse of 'x' (calculate if necessary).
+  i <- x$getinverse()
+  if(!is.null(i)) {
+    message('getting cached data')
+    return(i)
+  }
+  data <- x$get()
+  i <- solve(data)
+  x$setinverse(i)
+  i
 }
