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RE: [OT] Excel Golf: Unix Time to Excel Time in one line

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From:
McGlinchy, Alistair
Date:
October 28, 2004 07:00
Subject:
RE: [OT] Excel Golf: Unix Time to Excel Time in one line
Message ID:
8B653E54B22CC741B9D5AF5FD15126FCA1C45B@MSHVSMNSEXP0002.mnsexchange.adroot.marksandspencer.com
> From: Gerber, Christopher J [mailto:Christopher.J.Gerber@pfizer.com] 
> A couple more small changes:
> 
>  AND(X,Y) can be changed to (X)*(Y) in this case
> 
>  1/24*X can be changed to X/24
> 
>  2/24 can be changed to 1/12, although it's not shorter
> 
>  86400/24 can be changed to 3600
> 
> SO...
> 
> =25569+(A4/3600+DATE(YEAR(25569+A4/86400),5,1)-WEEKDAY(DATE(YE
> AR(25569+A4/86400),5,1),2)+1/24<25569+A4/86400)*(25569+A4/8640
> 0<DATE(YEAR(25569+A4/86400),11,1)-WEEKDAY(DATE(YEAR(25569+A4
> /86400),11,1),2)+1/12)/24

For dates between excluding 30 Dec to 2 Jan)
	YEAR(25569+A4/86400)
Is the same as (/secs per year)
	A4/31556868+70
The AND always returns false on the error conditions and for ordinary
January and December values, which is what we want.

The day of the week of 1 May and 1 November is the same every 28 years
between 1970 and 2099. 
	DATE(A2/31556868+14,5,1)-WEEKDAY(date)+1/24<25569+A2/86400
	DATE(A2/31556868+14,11,1)-WEEKDAY(date)+1/24<25569+A2/86400
Becomes 
	DATE(A2/31556868+14,5,1)-WEEKDAY(date)+1/24<5115+A2/86400
	DATE(A2/31556868+14,11,1)-WEEKDAY(date)+1/24<5115+A2/86400
In fact within this range 31556868 approx = 316^3  is OK  (75^4 doesn't
work)
	DATE(A2/316^3+14,5,1)-WEEKDAY(date)+1/24<5115+A2/86400
	DATE(A2/316^3+14,11,1)-WEEKDAY(date)+2/24<5115+A2/86400

I'm not to sure about the 86400/24 => 3600 tweak as
	a + b/86400 + c*d/24  != a + (b/3600+c)*d/24
	a + b/86400 + c*d/24  == a + (b/3600+(c)*(d))/24
Which requires two more () chars than it removes from 86400

Due to an absurdity of the Excel Date function 
	DATE(year,month,) 
Is 
	DATE(year,month,1) -1
So 1 May can be expressed as 
	DATE(A2/316^3+14,5,)-WEEKDAY(DATE(A2/316^3+14,5,))+25/24


Hence so far my best score is 161 with:
= 25569+A2/86400+(
	DATE(A2/316^3+14,5,)-WEEKDAY(DATE(A2/316^3+14,5,))+25/24
		<
	5115+A2/86400
)*(
	5115+A2/86400
		<
	DATE(A2/316^3+14,11,)-WEEKDAY(DATE(A2/316^3+14,11,))+25/24
)/24

Surely there must be a more direct way of getting 1 May ?  I played with
= (1 Jan )+ 121+(MOD(year,1)=0) but it never worked.


Cheers,

Alistair


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