cachematrix.R

makeCacheMatrix <- function(x = matrix()) {
    inv <- NULL
   set <- function(y) {
     x <<- y
     inv <<- NULL
   }
   get <- function() x
   setinv <- function(inverse) inv <<- inverse
   getinv <- function() inv
   list(set = set, get = get, setinv = setinv, getinv = getinv)
   }
## cacheSolve is a function which 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, ...) {
## Return a matrix that is the inverse of 'x'
   inv <- x$getinv()
   if(!is.null(inv)) {
     message("getting cached result")
     return(inv)
   }
   data <- x$get()
   inv <- solve(data, ...)
   x$setinv(inv)
   inv
  }