Peer assessment/Programming assignment2 submission

asantiago2014 · asantiago2014 · commit 1b68cefb144d · 2014-04-22T03:48:27.000+01:00
diff --git a/cachematrix.R b/cachematrix.R
@@ -1,15 +1,53 @@
 ## Put comments here that give an overall description of what your
 ## functions do
+## Peer Assessment / Programming Assignment 2 / R Programming course
 
-## Write a short comment describing this function
+## This function creates a special "matrix" object that can cache its inverse.
 
-makeCacheMatrix <- function(x = matrix()) {
+makeCacheMatrix <- function(matrix = matrix()) {
+  ## Return a special "matrix" that is the inverse of 'x', which is really a list containing a function to
+  ## 1. set the value of the matrix
+  ## 2. set the value of another matrix (is inverse)
+  ## 3. get the value of the matrix
+  ## 4. get the value of the matrix inverse
 
+  inverse <- NULL
+
+  setmatrix <- function(y) {
+    matrix <<- y
+    inverse <<- NULL
+  }
+
+  setinverse <- function(y) {
+    inverse <<- y
+  }
+
+  getmatrix <- function () matrix
+
+  getinverse <- function () inverse
+
+  list(setmatrix=setmatrix, setinverse=setinverse,
+       getmatrix=getmatrix, getinverse=getinverse)  
 }
 
 
-## Write a short comment describing this function
+## This function computes the inverse of the special "matrix" returned by makeCacheMatrix above.
+## If the inverse has already been calculated (and the matrix has not changed), then the cacheSolve
+## should retrieve the inverse from the cache.
 
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+  ## Return a matrix that is the inverse of 'x'
+
+  matrix <- x$getmatrix()
+  inverse <- x$getinverse()
+  
+  if(!is.null(inverse)) {
+    message("getting cached data")
+    return(inverse)
+  }
+  
+  inverse <- solve(matrix)
+  x$setmatrix(matrix)
+  x$setinverse(inverse)
+  inverse
 }
