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From: Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups: comp.lang.c
Subject: Re: Calculate date of Easter or Good Friday
Date: Sun, 03 Mar 2024 10:03:42 -0800
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vallor <vallor@cultnix.org> writes:

>> [...]
>
> ncal(1) has the -e and -o options for both Easters.  I went looking
> for the source of the Easter-computation code, found one copy here:
>
> https://github.com/lattera/freebsd/blob/master/lib/libcalendar/easter.c
>
> On Ubuntu with source repositories enabled, one can get the BSD
> ncal (with its bundled libcalendar) with
>
> $ apt-get source ncal
>
> I really wish the function easterg() was commented better.
>
> /* Compute Easter Sunday in Gregorian Calendar */
> date *
> easterg(int y, date *dt)
> {
>         int c, i, j, k, l, n;
>
>         n = y % 19;
>         c = y / 100;
>         k = (c - 17) / 25;
>         i = (c - c/4 -(c-k)/3 + 19 * n + 15) % 30;
>         i = i -(i/28) * (1 - (i/28) * (29/(i + 1)) * ((21 - n)/11));
>         j = (y + y/4 + i + 2 - c + c/4) % 7;
>         l = i - j;
>         dt->m = 3 + (l + 40) / 44;
>         dt->d = l + 28 - 31*(dt->m / 4);
>         dt->y = y;
>         return (dt);
> }
>
> The code is 27 years old.  I will not pretend to understand it.
> (Yet?) 

Seems like bad style to have two assignments to 'i'.  Easily
fixable simply by adding another variable.