/* NetRexx */
options replace format comments java crossref symbols nobinary

numeric digits 1000 -- allow very large numbers
parse arg rows .
if rows = '' then rows = 11 -- default to 11 rows
printPascalTriangle(rows)
return

-- -----------------------------------------------------------------------------
method printPascalTriangle(rows = 11) public static
  lines = ''
  mx = (factorial(rows - 1) / factorial(rows % 2) / factorial(rows - 1 - rows % 2)).length() -- width of widest number

  loop row = 1 to rows
    n1 = 1.center(mx)
    line = n1
    loop col = 2 to row
      n2 = col - 1
      n1 = n1 * (row - n2) / n2
      line = line n1.center(mx)
      end col
    lines[row] = line.strip()
    end row

  -- display triangle
  ml = lines[rows].length() -- length of longest line
  loop row = 1 to rows
    say lines[row].centre(ml)
    end row

  return

-- -----------------------------------------------------------------------------
method factorial(n) public static
  fac = 1
  loop n_ = 2 to n
    fac = fac * n_
    end n_
  return fac /*calc. factorial*/