completed assigment

rzijp · rzijp · commit 85f672e0272a · 2014-04-27T15:13:25.000+02:00
diff --git a/cachematrix.R b/cachematrix.R
@@ -1,15 +1,49 @@
 ## Put comments here that give an overall description of what your
 ## functions do
 
-## Write a short comment describing this function
-
+## function makeCacheMatrix returns a list of functions that provide 
+## cache capabilities to input variable x
 makeCacheMatrix <- function(x = matrix()) {
-
+    
+    # Define a cache variable that is empty
+    invCache <- NULL
+    # Define function to set the value of x and to clear the cache
+    set <- function(y) {
+        x <<- y
+        invCache <<- NULL
+    }
+    # Define the function to get the value of x, simply returning x
+    get <- function() x
+    # Define function to fill the cache
+    setinv <- function(inv) invCache <<- inv
+    # Define function to get the cache content
+    getinv <- function() invCache
+    # Return list of functions
+    list(set = set, get = get,
+         setinv = setinv,
+         getinv = getinv)
 }
 
 
-## Write a short comment describing this function
+## Function cacheSolve returns the inverse of input matrix x (assumption 
+## that x is always invertible). The inverse is cached if not done so
+## before, and if already cached this cache is returned directly and the 
+## inverse calculation is skipped
 
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+    ## Return a matrix that is the inverse of 'x'
+    # get the cached inverse of x
+    inv <- x$getinv()
+    # If the obtained cached is filled, return the cache
+    if(!is.null(inv)) {
+        message("getting cached data")
+        return(inv)
+    }
+    # Apparently the cache was empty, now calculate the inverse
+    data <- x$get()
+    inv <- solve(data, ...)
+    # Store the calculated inverse in the cache
+    x$setinv(inv)
+    # Return the inverse of x
+    inv
 }
