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From: "Daniel J. Long" <longdj@cat.com>
Subject: Re: language wars (results 13 September) last posting
Date: 1996/09/19
Message-ID: <32414A27.14E@cat.com>#1/1
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Date: 1996-09-19T00:00:00+00:00
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James Giles wrote (with deletions) :
>
> > Skeptics are invited to write a program to do the calculation for
> > themselves.
> 
> Assuming that *you* have done so, please have the courtesy to run it
> 2800 years and note that the 13th is equidistributed in weekdays.
> Then you can come back and apologise.  You have to run it more than
> 400 years because you have to go through a complete cycle of exceptions
> to the century rule.
> 
> J. Giles
> Ricercar Software


Ok, here is my program, written in Smalltalk, to calculate the
distribution
of Friday the 13ths for a 2800 year period from 1996 to 4795.  BTW,
Friday did
turn out to be the most likely 13th.

Dan


| anArray |
anArray := Array new: 7 withAll: 0.
1996 to: 4795 do: [:year |
	1 to: 12 do: [:month | | day |
		day := (Date newDay: 13 monthNumber: month year: year) weekdayIndex.
		anArray at: day put: ((anArray at: day) + 1)]].
anArray inspect

Result:  Mon  Tues Wed  Thur Fri  Sat  Sun
       #(4795 4795 4809 4788 4816 4788 4809)