Author: John Merlino
Date: 12:40:32 05/23/01
Go up one level in this thread
On May 23, 2001 at 15:12:17, Dann Corbit wrote:
>On May 23, 2001 at 14:44:32, stuart taylor wrote:
>
>>
>>>E:\nr\fixed>type badluk.c
>>>#include "nr.h"
>>>#define ZON -5.0
>>>#define IYBEG 2000
>>>#define IYEND 2100
>>>
>>>int main(void)
>>>{ /* Program BADLUK */
>>> int ic, icon, idwk, im, iyyy, n;
>>> double timzon = ZON / 24.0, frac;
>>> long jd, jday;
>>>
>>> printf ("\nFull moons on Friday the 13th from %5d to %5d\n", IYBEG, IYEND);
>>> for (iyyy = IYBEG; iyyy <= IYEND; iyyy++)
>>> {
>>> for (im = 1; im <= 12; im++)
>>> {
>>> jday = julday (im, 13, iyyy);
>>> idwk = (int) ((jday + 1) % 7);
>>> if (idwk == 5)
>>> {
>>> n = (int) (12.37 * (iyyy - 1900 + (im - 0.5) / 12.0));
>>> icon = 0;
>>> for (;;)
>>> {
>>> flmoon (n, 2, &jd, &frac);
>>> frac = 24.0 * (frac + timzon);
>>> if (frac < 0.0)
>>> {
>>> --jd;
>>> frac += 24.0;
>>> }
>>> if (frac > 12.0)
>>> {
>>> ++jd;
>>> frac -= 12.0;
>>> }
>>> else
>>> frac += 12.0;
>>> if (jd == jday)
>>> {
>>> printf ("\n%2d/13/%4d\n", im, iyyy);
>>> printf ("%s %5.1f %s\n", "Full moon", frac,
>>> " hrs after midnight (EST)");
>>> break;
>>> }
>>> else
>>> {
>>> ic = (jday >= jd ? 1 : -1);
>>> if (ic == (-icon))
>>> break;
>>> icon = ic;
>>> n += ic;
>>> }
>>> }
>>> }
>>> }
>>> }
>>> return 0;
>>>}
>>>
>>>E:\nr\fixed>badluk
>>>
>>>Full moons on Friday the 13th from 2000 to 2100
>>>
>>>10/13/2000
>>>Full moon 4.0 hrs after midnight (EST)
>>>
>>> 9/13/2019
>>>Full moon 23.6 hrs after midnight (EST)
>>>
>>> 8/13/2049
>>>Full moon 3.8 hrs after midnight (EST)
>>>
>>> 2/13/2082
>>>Full moon 1.9 hrs after midnight (EST)
>>>
>>>10/13/2084
>>>Full moon 15.2 hrs after midnight (EST)
>>>
>>> 6/13/2098
>>>Full moon 15.6 hrs after midnight (EST)
>>>
>>>
>>I DON'T FOLLOW!
>
>Sorry. An incredibly obtuse joke. I used to wait on pins and needles for Bruce
>to release Ferret or sell Ferret or whatever with Ferret so that the ordinary
>citizen could get their hands on a copy. After several years of this, I finally
>figured out that Bruce is in no big hurry to make Ferret available.
>
>I don't know how to calculate a "blue moon" so (instead) I calculated the nearly
>as rare 'full moon on Friday the 13th.' Coincidentally, the one in 2019 is just
>minutes before midnight. Owwwooooooooh!
>9/13/2019: Full moon 23.6 hrs after midnight (EST)
>
>Our best chance to get a copy this millenium.
Do you mean you do not know how to calculate a blue moon, or that you do not
know what one is, so you CANNOT calculate it?
If the latter, then a blue moon is defined as the second full moon in a single
calendar month -- not that rare, actually.... There's one in November of this
year!
jm
p.s. Amusingly enough, this definition is NOT the "original" definition, but
replaced the older one due to a writing error in a popular astronomical magazine
(Sky and Telescope) in 1946. The "second full moon in a single calendar month"
definition has stuck since then.
But the original definition, going back to very old Farmers' Almanacs, defines a
blue moon as "the third full moon in a season that has four full moons". Far
more obscure, and not as trivial to calculate.
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