Update cachematrix.R

mingcho · mingcho · commit 110e6e9d6bcd · 2014-04-16T20:23:14.000-07:00
diff --git a/cachematrix.R b/cachematrix.R
@@ -1,8 +1,18 @@
 ## Put comments here that give an overall description of what your
 ## functions do
 
-## Write a short comment describing this function
+# makeCacheMatrix store matrix and its inverse
+# cacheSolve return the inverse of the matrix
+
+# For example, if A is a square invertible matrix:
+# B <- makeCacheMatrix(A) create the object with matrix A.
+# B$get() returns the matrix A.
+# cacheSolve(B) calculate the inverse of A and cache in B if matrix inverse is not yet cached.
+# cacheSolve(B) return the matrix inverse of A from cache if cacheSolve(B) is called previously.
+# B$getinverse() returns the inverse of A if the inverse is already cached.
 
+## Write a short comment describing this function
+# makeCacheMatrix creates an object from a matrix.
 makeCacheMatrix <- function(x = matrix()) {
 	m <- NULL
         set <- function(y) {
@@ -19,7 +29,7 @@ makeCacheMatrix <- function(x = matrix()) {
 
 
 ## Write a short comment describing this function
-
+# cacheSolve return the matrix inverse either from solve() or from cache.
 cacheSolve <- function(x, ...) {
         ## Return a matrix that is the inverse of 'x'
         m <- x$getinverse()
