(defun pi (nr)
  (set max (* nr 4))
  (array a max)
  (set m nr)
  (for i 0 max (set (a i) 0))
  (set k (- (/ (* m 3321) 1000) 1) )
  (for n k 1
    (set (a 0) (+ (a 0) 2))
    (set p (+ 1 (* 2 n)))
    (set c 0)
    (for i 0 m
      (set c (+ (* 10 c) (* n (a i))))
      (set (a i) (/ c p))
      (set c (- c (* (a i) p)))
    )
    (locate 5 20)
    (write n '    ' '')
  )
  (for i m 1
    (if (greater (a i) 9)
      (do
        (set (a i) (- (a i) 10) )
        (set (a (- i 1)) (+ (a (- i 1)) 1))
      )
    )
  )
  (cls)
  (write)
  (write 'pi=3.' '')
  (for i 1 m
    (write (a i) '')
  )
  (write)
)


(window 0 11 400 150 'PI calc')
(write '#of decimals: ' '')
(set deci (readint))
(write 'busy ....')
(pi deci)
(write)