cachematrix.R

cachematrix.R

@@ -1,15 +1,51 @@
-## Put comments here that give an overall description of what your
-## functions do
-
-## Write a short comment describing this function
-
-makeCacheMatrix <- function(x = matrix()) {
-
-}
-
-
-## Write a short comment describing this function
-
-cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
-}
+## These functions cache the inverse of a matrix so that the inverse
+## is computed only once. If the inverse has already been calculated,
+## the cached value is returned instead of recomputing it.
+
+## Create a special matrix object that can store a matrix and cache
+## its inverse.
+
+makeCacheMatrix <- function(x = matrix()) {
+  inv <- NULL
+
+  set <- function(y) {
+    x <<- y
+    inv <<- NULL
+  }
+
+  get <- function() x
+
+  setinverse <- function(inverse) {
+    inv <<- inverse
+  }
+
+  getinverse <- function() {
+    inv
+  }
+
+  list(
+    set = set,
+    get = get,
+    setinverse = setinverse,
+    getinverse = getinverse
+  )
+}
+
+## Return the cached inverse if available; otherwise compute the
+## inverse, cache it, and return it.
+
+cacheSolve <- function(x, ...) {
+  inv <- x$getinverse()
+
+  if (!is.null(inv)) {
+    message("getting cached data")
+    return(inv)
+  }
+
+  data <- x$get()
+  inv <- solve(data, ...)
+
+  x$setinverse(inv)
+
+  inv
+}