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From: cdl@mplvax.EDU (Carl Lowenstein)
Newsgroups: alt.sources
Subject: Re: Postscript Calendar Program
Keywords: leap year
Message-ID: <1011@mplvax.EDU>
Date: 20 Sep 89 23:08:13 GMT
References: <1979@diamond.warwick.ac.uk> <MAP.89Sep19151406@gaak.LCS.MIT.Edu> <7878@robin.cs.nott.ac.uk>
Reply-To: cdl@mplvax.ucsd.edu.UUCP (Carl Lowenstein)
Organization: U.C. San Diego, Marine Physical Laboratory
Lines: 22

In article <7878@robin.cs.nott.ac.uk> dre@cs.nott.ac.uk (David Evans) writes:
>I had a quick look through the PostScript code and noticed that the leap year
>calculation is wrong - despite being fixed!  Centuries are leap years only
>if divisible by 400, not 1000!  The "isleap" procedure should be changed . . .

So also should the "startday" procedure similarly be changed to:

	off 400 idiv add	% Gregorian correction

This makes the calendar repeat every 400 years, as it really does.
Of course, you won't notice this until the year 2400.

For us people who use inch-size paper, there are various x-translation
constants that should be somewhat smaller, like 190 instead of 200 picas.
Really these should be paramaterized, but this is left as an exercise
for the student.


-- 
	carl lowenstein		marine physical lab	u.c. san diego
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