Steem Dollar Compound Interest Collecting Bot 复利收集机器人

You know, if you hold Steem Dollars, either in liquid form or savings, you'll earn interest. Compound interest is explained in this wikipedia article.

[Image source, by Jelson25 - Own work, CC BY-SA 3.0]

However, the interest will only be paid when the balance of your account changes. The algorithm is:

• there is a last interest paid time field stored in your account
• every time after balance changed, if last interest paid time is not less than 30 days in the past, interest will be calculated and paid
• a simplified formula is: interest = average_balance_since_last_interest_pay * daily_interest_rate * days
• daily interest rate is calculated as annual_rate / 365. For example, current annual interest rate is 10%, daily rate is calculated as 10% / 365 = 0.0274%.

If you have 1000 Steem Dollars, and

• if you move funds once a month, the interest paid to you will be around 1000 * (1 + 10% / 12)^12 - 1000 = 104.7 SBD (calculation link)
• if you move funds once a year, the interest paid to you will be 1000 * 10% = 100 SBD

Which means, if you don't move funds in time, you'll loss the compound interest.

How about someone make a bot to collect compound interest for its subscribers? The bot only need to send 0.001 SBD to subscriber's accounts once every month. Perhaps with a subscription fee of 0.002 SBD per account per month?

--- end of English part ---

你知道，如果你持有 Steem Dollar ，不管是在流动账户还是储蓄账户，你会挣到利息。复利介绍参见这篇英文文章）（如果链接打不开，请自己百度）。

[图 来源， 作者 Jelson25 - 自创， CC BY-SA 3.0]

但是，利息只会在你的账户余额发生变化时才会支付。算法是：

• 账户里存储了一个“上次利息支付时间”
• 每次当余额发生变化时，如果上次利息支付时间在30天以前，则会计算并支付利息
• 简化公式是：利息 = 上次支付利息后平均每天账户余额 * 天利率 * 天数
• 天利率计算公式是 年利率 / 365。比如现在年利率是 10% ，天利率计算公式是 10% / 365 = 0.0274。

比如你账户里有 1000 Steem Dollar，并且

• 如果你每月动一次账户，则一年总利息大约是 1000 * (1 + 10% / 12)^12 - 1000 = 104.7 SBD (计算链接)
• 如果你每年动一次账户，则一年总利息是 1000 * 10% = 100 SBD

这意味着如果你没有及时动一下账户，你将不会获得复利。

如果有个机器人，专门为客户收集利息，会怎么样？这个机器人只需要每个月给客户转账 0.001 SBD 即可。可能机器人可以设置个每月每账户 0.002 SBD 的服务费。