/* NetRexx */

options replace format comments java crossref savelog symbols

numeric digits 210000                  /*prepare for some big 'uns.     */
parse arg x y .                        /*allow a single number or range.*/
if x == '' then do                     /*no input? Then assume -30-->+30*/
  x = -30
  y = -x
  end

if y == '' then y = x             /*if only one number, show fib(n)*/
loop k = x to y                   /*process each Fibonacci request.*/
  q = fib(k)
  w = q.length                    /*if wider than 25 bytes, tell it*/
  say 'Fibonacci' k"="q
  if w > 25 then say 'Fibonacci' k "has a length of" w
  end k
exit

/*-------------------------------------FIB subroutine (non-recursive)---*/
method fib(arg) private static
  parse arg n
  na = n.abs

  if na < 2 then return na             /*handle special cases.          */
  a = 0
  b = 1

  loop j = 2 to na
    s = a + b
    a = b
    b = s
    end j

  if n > 0 | na // 2 == 1 then return  s /*if positive or odd negative... */
                          else return -s /*return a negative Fib number.  */