The calculation of the number of RU-days __ Standard

A paragraph of Mr. Xu Jianwei's explanation. He was mentioned in the Help file in the "Longevity Almanac" software.


Number of Julian days (abbreviated to Julian Day)
The number of Julian days refers to the number of days from the beginning of 4712 and the number of the days of the day, usually recorded as JD (* *). Traditionally, the number of Julian's dates began 12 o'clock Greenwich, the world. In the case of Mechanics (or almanac), this count is usually expressed as "Julian Almanac Day", that is, JDE (* *), where e is only a representation, that is, the day is strictly counted at 86,400 standard seconds long. For example:
April 1977 26.4 UT = JD 2443 259.9
April 1977 26.4 TD = JDE 2443 259.9
The calculation of Julian's Day
Set Y to the given year, M is the month, and D is the month date (can be with decimals).
If M > 2,y and M are invariant, if M = 1 or 2, to y–1 y, to m+12 m, in other words, if the date is in January or February, it is considered to be in the previous year of 1 March or 1 April.
The Gregorian calendar has: a = INT (y/100) B = 2-a + int (A/4)
For the Julian calendar, take B = 0
The required Julian Day is: JD = INT (365.25 (y+4716)) +int (30.6001 (m+1)) +d+b-1524.5
Using value 30.6 instead of 30.6001 is correct, but we still use 30.6001 to make sure that we always get the right integers. In fact, 30.601 or even 30.61来 can replace 30.6001. For example, 5 times 30.6 is exactly equal to 153, whereas most computers cannot accurately represent 30.6, which results in a 152.999 9998 result, with an integer part of 152, so that the JD is not correct.