cachematrix.R

## makeCacheMatrix function creates a special "matrix" object,
## that can cache its inverse.
## Assumption : The matrix supplied is always invertible.
makeCacheMatrix <- function(x = matrix()){    
    
    i <- NULL    
    
    set <- function(y) {
        x <<- y
        i <<- NULL
    }
    get <- function() x
    setinverse <- function(inverse) i <<- inverse
    getinverse <- function() i    
    list(set = set, get = get,
         setinverse = setinverse,
         getinverse = getinverse)        
}

## cacheSolve function computes the inverse of the special "matrix",
## returned by makeCacheMatrix above. If the inverse 
## has already been calculated (and the matrix has not changed), 
## then the cachesolve should retrieve the inverse from the cache.
cacheSolve <- function(x, ... ){
    
    i <- x$getinverse()
    
    if(!is.null(i)) {        
        message("getting cached data")
        return(i)
    }
    
    data <- x$get()    
    i <- solve(data)
    x$setinverse(i)        
    i
}