cachematrix.R

## makeCacheMatrix creates a special matrix object, and then cacheSolve calculates the inverse of it.
## If the inverse matrix has already been calculated, it will find it in the cache and then return it. 

makeCacheMatrix <- function(x = matrix()) {
	
	inv <- NULL
	
	set <- function(y) {
		x <<- y         #provides a default if cacheSolve has not yet been used
		inv <<- NULL    #provides a default if cacheSolve has not yet been used
	}
        
	get <- function() x
	
	setinv <- function(inverse) inv <<- inverse
	
	getinv <- function() inv
	
	list(set = set, get = get, setinv = setinv, getinv = getinv)
}

## The function cacheSolve returns the inverse of a matrix x created in the makeCacheMatrix function.
## If the cached inverse is available, cacheSolve retrieves it, if not, it computes and retrieves it from the cache.

cacheSolve <- function(x, ...) {
	
	inv <- x$getinv()   #if an inverse has already been calculated this gets it
	
	if(!is.null(inv)) {
		message("getting cached inverse matrix")
		return(inv)
	}
        
	else {
		inv <- solve(x$get())   #compute the value of the inverse of the input matrix
		x$setinv(inv)
	}
	
	inv  #return the inverse
}