cachematrix.R commit

olarina · olarina · commit 160920462aa0 · 2019-02-20T10:27:57.000+01:00
diff --git a/cachematrix.R b/cachematrix.R
@@ -1,15 +1,44 @@
-## Put comments here that give an overall description of what your
-## functions do
+## Below are two functions that are used to create a special object that stores
+## a numeric matrix and caches its inversion
 
-## Write a short comment describing this function
+## The first function, makeCacheMatrix creates a special "vector"
+## which is really a list containing a function to
 
-makeCacheMatrix <- function(x = matrix()) {
-##test
-}
+## 1. set the value of the matrix
+## 2. get the value of the matrix
+## 3. set the value of the inversion
+## 4. get the value of the inversion
 
+makeCacheMatrix <- function(x = matrix())
+{
+    inv <- NULL
+    set <- function(y)
+    {
+        x <<- y
+        inv <<- NULL
+    }
+    get <- function() x
+    setinv <- function(i) inv <<- i
+    getinv <- function() inv
+    list(set = set, get = get, setinv = setinv, getinv = getinv)
+}
 
-## Write a short comment describing this function
+## The following function calculates the inversion of the special "vector"
+## created with the makeCacheMatrix function. It first checks if the inversion
+## has already been calculated. If so, it gets the inversion from the cache and
+## skips the computation. Otherwise, it calculates the inversion of the data
+## and sets the value of the inversion in the cache via the setinv function.
 
-cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+cacheSolve <- function(x, ...)
+{
+    inv <- x$getinv()
+    if (!is.null(inv))
+    {
+        message("getting cached data")
+        return(inv)
+    }
+    data <- x$get()
+    inv <- solve(data, ...)
+    x$setinv(inv)
+    inv
 }
