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Converts the current (or provided) date to a Keppel date. Used by Template:Keppel date.

Begin with the following inputs:

First, define the following:

$\text{year} \bmod 400 = 0$ $\text{year} \bmod 4 = 0\text{ and not }\text{year} \bmod 100 = 0$

$\text{year} \bmod 4 = 2$

$\text{year} \bmod 239 = 65$

earthYearLength: If it is an Earth leap year, 366; else, 365.
yearLength: Start with 389.; If it is a Keppel leap year (schedule 1), add one.; If it is a Keppel leap year (schedule 2), add one.
rolloverOffset: If it is an Earth leap year, 79; else, 78.

To calculate the result:

$\text{year} - 892$

$\frac{\text{yearLength} * (\text{yday} - \text{rolloverOffset})}{\text{earthYearLength}} \bmod{\text{yearLength}}$

$\lceil \frac{\text{yday}}{32} \rceil$

$\lfloor \text{yday} - (\text{lythryd} - 1) * 32 \rfloor$

@@ Line 31: / Line 31: @@
 <math mode="display">\text{year} - 892</math>
 :If <code>yday</code> is less than 79, subtract one.
-;<code>ydayPre</code>
+;<code>yday</code>
 <math mode="display">\frac{\text{yearLength} * (\text{yday} - \text{rolloverOffset})}{\text{earthYearLength}} \bmod{\text{yearLength}}</math>
 :If <code>yday</code> is less than or equal to zero, then add <code>yearLength</code>.