Coursera programming assignment rdpeng#2

aenaus · aenaus · commit 4ebaa9d439a2 · 2014-05-21T18:17:42.000+03:00
The two functions needed in the assignment.
diff --git a/cachematrix.R b/cachematrix.R
@@ -1,15 +1,47 @@
-## Put comments here that give an overall description of what your
-## functions do
-## This is for a test commit to my repo
-## Write a short comment describing this function
+## "makeCacheMatrix" creates a function that will take x which is assumed to be an invertible matrix and
+##will return a list of functions that are able to set and get the matrix and its inverse
+##The <<- operator is used to assign a value to a variable in the parent environment
+##set nullifies the m which is the inverse matrix
+##get returns the matrix
+##setinv sets the inverse of the matrix
+##getinv returns the inverse of the matrix
+##The output is a list containing those functions
 
-makeCacheMatrix <- function(x = matrix()) {
+makeCacheMatrix<-function (x  =as.matrix()){
+  m <- NULL
 
+  set <- function (y) {  
+    x <<- y
+    m <<- NULL
+  }
+  get <- function() x
+  setinv <- function (solved) {
+    m <<- solved
+  } 
+  getinv <- function () m
+  list (set = set, 
+        get = get, 
+        setinv = setinv,
+        getinv = getinv)
+  
 }
 
+##"cacheSolve" creates a function that will take x, a list of functions that is the output of a matrix
+##matrix processed with the "makeCacheMatrix" function and will calculate it's inverse with the solve
+##function, unless this has already done.Then, the cached result will be returned
+##First the funtion assigns m the value of the inverse matrix, this is either NULL or something computed
+##in a previous invoke of the "cacheSolve" function. If m is not NULL then the cached value is returned.
+##If m is NULL it calculates the inverse matrix and assigns this to m with the  "setinv". 
+##In the first invoke of "cacheSolve" m is always NULL
 
-## Write a short comment describing this function
-
-cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+cacheSolve<-function(x, ...) {
+  m<-x$getinv()
+  if(!is.null(m)){
+    message("getting cached data")
+    return(m)
+  }
+  data <-x$get()
+  m<- solve(data, ...)
+  x$setinv(m)
+  m
 }
