From: Michael J Gruber <git@drmicha•warpmail.net>
To: Jeff King <peff@peff•net>
Cc: git@vger•kernel.org
Subject: Re: [PATCH] date: avoid "X years, 12 months" in relative dates
Date: Wed, 20 Apr 2011 13:00:07 +0200 [thread overview]
Message-ID: <4DAEBCB7.80707@drmicha.warpmail.net> (raw)
In-Reply-To: <20110420101800.GA24035@sigill.intra.peff.net>
Jeff King venit, vidit, dixit 20.04.2011 12:18:
> 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. :)
Also, this is inside "if (diff < 1825)", so no matter where diff comes
from, "long" is really long enough.
Cheers,
Michael
prev parent reply other threads:[~2011-04-20 11:00 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-20 5:24 [PATCH/RFH] date: avoid "X years, 12 months" in relative dates Jeff King
2011-04-20 9:12 ` [PATCH] " Michael J Gruber
2011-04-20 10:18 ` Jeff King
2011-04-20 11:00 ` Michael J Gruber [this message]
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