[LEAPSECS] Reliability

[blb8 at po.cwru.edu]

> From: Rob Seaman <seaman at noao.edu>

> ...

> Like I keep saying, the mean solar day is trivial to compute from the  

> sidereal day.  Look at it this way, there are "really" 366.25 days per  

> year.  That extra day just gets sliced and diced among all the others.


Nice, now we have extra days!

A "leap year" is every four years except every one hundred years except every four hundred years.  Put another way, if Y is the number of the year then Y is a leap year if:  (Y%4==0)&&((Y%100!=0)||(Y%400==0)) where that's the modulus operator, of course.  In a four-hundred year cycle, that's 24 leap years per century except the start of the century (minus one), and then one leap year at the start of the millenium (minus one).

That's 303*365+97*366=146097 days for an average of 365.2425 days per year.  Woo!

I guess being on break for two weeks means I haven't gotten my fill of teaching arithmetic.



Brian Blackmore
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