cachematrix.R

## The functions below cache the inverse of a matrix
##  rather than compute it repeatedly

## This function creates a special "matrix" object that can cache its inverse.
makeCacheMatrix <- function(x = matrix()) {
  inv <- NULL
  set <- function(y) {
    x <<- y
    inv <<- NULL
  }
  get <- function() x
  setinv <- function(iv) inv <<- iv
  getinv <- function() inv
  list(set = set, get = get,
       setinv = setinv,
       getinv = getinv)
}


## This function computes the inverse of the special "matrix" 
##   returned by makeCacheMatrix above. 
##   If the inverse has already been calculated, then the 
##   cachesolve should retrieve the inverse from the cache.
cacheSolve <- function(x, ...) {
  iv <- x$getinv()
  if(!is.null(iv)) {
    message("getting cached data")
    return(iv)
  }
  data <- x$get()
  iv <- solve(data)
  x$setinv(iv)
  iv
}