Wikipedia:Reference desk/Archives/Computing/2024 February 26

= February 26 =

Windows 11 multiple desktops: app always across desktops
Windows 11 has (at last!) introduced multiple desktops. I know how to mark a window as being available across all desktops (either that window, or all windows of that app). Is there a way to set that whenever a particuar app is opened, it will automatically be available across all desktops? I haven't found one. ColinFine (talk) 10:44, 26 February 2024 (UTC)

Easter date list
Is there any tool that lists years of Easter Sunday occurring at any given date until very many millennia from now? The table at Robin van Gent's Easter calculator lists them until year 3000, and I have downloaded an external web application that makes lists until 4099, but I want to make lists of Easter occurring on a rare date (like 22, 23, 24 March or 23, 24, 25 April) until more than 10,000 years from now and in such calculation I use the van Gent's calculator. For example, if I want to make a list of every occurrence of Easter on 22 March, then I test Easter date on all years when 22 March is on Sunday and write down all years that actually have Easter on 22 March. But is there an easier tool to do this? --40bus (talk) 11:16, 26 February 2024 (UTC)
 * Not an app, but this site has a csv file you can download that lists all the Easter dates for 1583 to 4099.  Since it is a plain text file you can just search for "March 22" to get those dates. RudolfRed (talk) 05:32, 27 February 2024 (UTC)
 * Since the exact date of Easter Sunday by definition is determined by a combination of the March Equinox and the occurrence of a full moon shortly thereafter, one could perhaps calculate the date themselves, by looking up future dates for the occurrence of full moons. Powerful computations have been run on our behalf to determine the precise date of the Moon's phases and other extraterrestrial phaenomena. Pablothepenguin (talk) 12:26, 27 February 2024 (UTC)
 * Easter is the first Sunday after the Paschal full moon. This date cannot be determined by astronomical calculations, because the Pascal full moon is not an actual astronomical event. As our article says "This "full moon" does not currently correspond directly to any astronomical event, but is instead the 14th day of a lunar month, determined from tables. It may differ from the date of the actual full moon by up to two days." CodeTalker (talk) 02:39, 28 February 2024 (UTC)
 * Our article on the date of Easter has all the information you need (or ought to have; I haven't checked). If you can program a bit, you can write your own tool to find the date of Easter in the far future. That is, assuming the rules won't change. PiusImpavidus (talk) 13:01, 27 February 2024 (UTC)
 * Python code for computing the date of Easter can be found here. To select and print out lists of years with Easter occurring on a rare date is then a very simple exercise. --Lambiam 21:33, 27 February 2024 (UTC)


 * I have two books by Jean Meeus, Astronomical Formulae for Calculators and Astronomical Algorithms which do this, and a lot more. Unfortunately they are both boxed up for a move.  I think the former has BASIC code for the calculations.  The latter gives all of the details you need to write a program (for many astronomical calculations).  One thing - you need to make sure that any program or algorithm is valid for the date range you want.  Some of them are only valid to, say, 2099. Bubba73 You talkin' to me? 22:04, 27 February 2024 (UTC)
 * The cal utility (standard on most Linux systems) can also calculate the date of easter in a particular year: ncal -e [year]. Put it in a loop in a bash script to find interesting dates. It goes up to the year 9999. PiusImpavidus (talk) 10:39, 28 February 2024 (UTC)


 * Well, by main Meeus book was not packed up. Chapter 8 gives a short method for calculating the date of Easter.  Some of these have been mentioned, but the book says:


 * This method doesn't have the exceptions that the method by Gauss has
 * The full moon is not the astronomical full moon - it is when the church says it is (a certain number of days)
 * Likewise, the Vernal Equinox is not the actual day - the church dictates it to be March 21, but the real one can be 1 or 2 days from that.
 * This method is good for the Gregorian calendar for 1583 onward.
 * It cycles in 5,700,000 years. Bubba73 You talkin' to me? 02:31, 1 March 2024 (UTC)
 * So I got at least the last bit right (see the last sentence at archived RD topic Coincidence of Ash Wednesday and Valentine's Day). --Lambiam 13:53, 2 March 2024 (UTC)
 * Right you were. Bubba73 You talkin' to me? 02:46, 3 March 2024 (UTC)
 * I have a program that puts easter into a calender but the line for it is just
 * date_event( datetime.date.fromordinal(dateutil.easter.easter(year).toordinal-2), "Easter Weekend" );
 * The -2 was to give Easter Friday instead of Sunday. Not very illuminating but it works. NadVolum (talk) 19:31, 11 March 2024 (UTC)
 * J R Stockton's page on Easter is a great resource; though the site died in 2015 there's the Internet Archive version or this mirror. Lots of code snippets there you can copy, or you can just scroll down to "Compressed Tables" and put in a range to get all the Easter dates by year and all the years for a given Easter date (it takes a few seconds to do the full 5,700,000 year cycle on my machine). Arcorann (talk) 12:27, 13 March 2024 (UTC)