From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeff King <peff@peff.net>
Subject: Re: [PATCH] date: avoid "X years, 12 months" in relative dates
Date: Wed, 20 Apr 2011 06:18:00 -0400
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To: Michael J Gruber <git@drmicha.warpmail.net>
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On Wed, Apr 20, 2011 at 11:12:11AM +0200, Michael J Gruber wrote:

> Implement this differently with months of size
> 
>   onemonth = 365/12
> 
> so that
> 
>   totalmonths = (long)( (days + onemonth/2)/onemonth )
>   years = totalmonths / 12
>   months = totalmonths % 12
> 
> In order to do this without floats, we write the first formula as
> 
>   totalmonths = (days*12*2 + 365) / (365*2)

Well now I feel like an idiot. Algebra to the rescue.

The extra multiplications introduce the possibility of overflow, but
since the number of days was arrived at by dividing an unsigned long
number of seconds by 86400, we are guaranteed to have room to multiply
by 24. :)

So looks good to me.

-Peff