cachematrix.R

## Put comments here that give an overall description of what your
## functions do

## Write a short comment describing this function

makeCacheMatrix <- function(x = matrix()) 
{
    
    # makeCacheMatrix creates a list containing a function to
    # 1. set the value of the matrix
    # 2. get the value of the matrix
    # 3. set the value of inverse of the matrix
    # 4. get the value of inverse of the matrix
    
    inv <- NULL
    set <- function(y) 
    { x <<- y
      inv <<- NULL }
    get <- function()
    { x }
    setinverse <- function(inverse)
    { inv <<- inverse }
    getinverse <- function()
    { inv} 
    list(set=set, get=get, setinverse=setinverse, getinverse=getinverse)
}


## Write a short comment describing this function

# The function returns the inverse of the matrix. It first checks if
# the inverse has already been calculated. 
# If so, it gets the result and skips the computation. 
# If not, it computes the inverse, sets the value in the cache via
# setinverse function.

# This function assumes that the matrix is always invertible.

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
}

# #Sample run:
# > baseMatrix = rbind(c(1, 2), c(3, 4))
# > cacheMatrix = makeCacheMatrix(x)
# > cacheMatrix$get()
#       [,1]  [,2]
# [1,]  1.00 -0.25
# [2,] -0.25  1.00
# 
# #No cache in the first run
# > cacheSolve(cacheMatrix)
#           [,1]      [,2]
# [1,] 1.0666667 0.2666667
# [2,] 0.2666667 1.0666667
# 
# #Retrieving from the cache in the second run
# > cacheSolve(cacheMatrix)
# #getting cached data.
#           [,1]      [,2]
# [1,] 1.0666667 0.2666667
# [2,] 0.2666667 1.0666667