Editing D'ni time conversion (section)

==== Algorithm 2. Julian Day Number to Gregorian Date ====

Using real arithmetic, calculate Gregorian Year, Month, Day, Hour, Minute, and Second from a Julian Day (JD) that was calculated according to Algorithm 1. The input JD is assumed to be a real number. Output values are assumed to be integers.

A. Extract the number of whole days and calculate the date:

<pre>    Z = INT(JD)
    G = Z - 0.25
    A = INT(G / 36524.25)
    B = A - (0.25 * A)
    Year = INT((G + B) / 365.25)
    C = Z + B - INT(365.25 * Year)
    Month = FIX(((5 * C) + 456) / 153)
    Day = C - FIX(((153 * Month) - 457) / 5)</pre>

B. If the month is 13 or 14, adjust the month and year to a January-1 starting point:

<pre>    if Month > 12 then
       Year = Year + 1
       Month = Month - 12
    end if</pre>

C. The year is in CE form, meaning that years prior to 1 CE will be 0 or negative. To change such years to BCE form, use the calculation shown below. If this conversion is used, the program should include a variable indicating whether the date is CE or BCE.

<pre>    if Year < 1 then Year = 1 - Year</pre>

D. If JD includes a fractional (time of day) part, extract the fraction and calculate the time:

<pre>    Z = (JD - INT(JD)) * 86400
    Hour = FIX(Z / 3600)
    R = Z - (Hour * 3600)
    Minute = FIX(R / 60)
    Second = R - (Minute * 60)</pre>