Implemented makeCacheMatrix & cacheSolve functions

glauco · glauco · commit bf5461413af1 · 2016-03-12T12:11:53.000-03:00
diff --git a/cachematrix.R b/cachematrix.R
@@ -1,15 +1,61 @@
-## Put comments here that give an overall description of what your
-## functions do
-
-## Write a short comment describing this function
+## Assignment: Caching the Inverse of a Matrix
 
+## Creates a cacheMatrix which consists of a list of functions that
+## operates on a provided matrix.
+##
+## Usage example:
+##
+## Given the following matrix:
+## > x <- matrix (c(1,2,3,4), nrow=2, ncol=2)
+## When I execute this function:
+## > cacheMatrix <- makeCacheMatrix(x)
+## Then it returns a list of functions that operate on the matrix
+## And I could get the matrix by executing:
+## > cacheMatrix$get()
+## And I could set a new matrix by executing:
+## > cacheMatrix$set(matrix(c(4,3,2,1), nrow=2, ncol=2))
 makeCacheMatrix <- function(x = matrix()) {
-
+        inverse <- NULL
+        get <- function() { x }
+        set <- function(newMatrix) {
+                x <<- newMatrix
+                inverse <<- NULL
+        }
+        getInverse <- function() { inverse }
+        setInverse <- function(newInverse) {
+                inverse <<- newInverse
+        }
+        list(get = get,
+             set = set,
+             getInverse = getInverse,
+             setInverse = setInverse)
 }
 
-
-## Write a short comment describing this function
-
+## Calculates and caches the inverse of a matrix.
+##
+## Usage example:
+##
+## Given the following cacheMatrix:
+## > cacheMatrix <- makeCacheMatrix(matrix(c(4,3,2,1), nrow=2, ncol=2))
+## When I execute this function:
+## > cacheSolve(cacheMatrix)
+## Then I get the inverse matrix:
+##      [,1] [,2]
+## [1,] -0.5    1
+## [2,]  1.5   -2
+## And I have now this inverse matrix cached on my cacheMatrix:
+## > cacheMatrix$getInverse()
+##      [,1] [,2]
+## [1,] -0.5    1
+## [2,]  1.5   -2
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+        inverse <- x$getInverse()
+        if(!is.null(inverse)) {
+                message("getting cached data")
+                return(inverse)
+        }
+        data <- x$get()
+        inverse <- solve(data)
+        x$setInverse(inverse)
+        inverse
 }
