created makeCacheMatrix() and cacheSolve()

Author: Necrum

cachematrix.R

@@ -1,15 +1,43 @@
-## Put comments here that give an overall description of what your
-## functions do
+## makeCacheMatrix() creates "matrix" object and
+## returns list of functions to manipulate it.
+## 
+## cacheSolve() returns the inverse of a matrix.
+## It first checks if the inverse of a matrix has already been calculated,
+## otherwise it calculates the inverse of a matrix and puts it to the cache
+##
+## Example:
+## a <- matrix(c(1,2,3,4), nrow=2, ncol=2)
+## m <- makeCacheMatrix(a)
+## cacheSolve(m)
 
-## Write a short comment describing this function
 
-makeCacheMatrix <- function(x = matrix()) {
+## Creates "matrix" object
 
+makeCacheMatrix <- function(x = matrix()) {
+    x_inverse <- NULL
+    set <- function(y) {
+            x <<- y
+            x_inverse <<- NULL
+    }
+    get <- function() x
+    setinverse <- function(inv) x_inverse <<- inv
+    getinverse <- function() x_inverse
+    list(set = set, get = get,
+         setinverse = setinverse,
+         getinverse = getinverse)
 }
 
 
-## Write a short comment describing this function
+## Calculates of gets from the cache the inverse of a "matrix" object
 
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+    inv <- x$getinverse()
+    if (!is.null(inv)) {
+        message("getting cached data")
+        return(inv)
+    }
+    data <- x$get()
+    inv <- solve(data)
+    x$setinverse(inv)
+    inv
 }