SYD Function

SYD.js

// Copyright (c) 2012 Sutoiku, Inc. (MIT License)

function SYD(cost, salvage, life, period) {
  // Return error if any of the parameters is not a number
  if (isNaN(cost) || isNaN(salvage) || isNaN(life) || isNaN(period)) return '#VALUE!';

  // Return error if life equal to 0 (zero)
  if (life === 0) return '#NUM!';

  // Return error if period is lower than 1 or greater than life
  if (period < 1 || period > life) return '#NUM!';

  // Truncate period if it is not an integer
  period = parseInt(period, 10);

  // Return straight-line depreciation
  return (cost - salvage) * (life - period + 1) * 2 / (life * (life + 1));
}