doomsday

doomsday, a MATLAB code which is given the year, month and day of a date, and uses John Conway's doomsday algorithm to determine the corresponding day of the week.

Licensing:

The information on this web page is distributed under the MIT license.

Languages:

doomsday is available in a C version and a C++ version and a Fortran90 version and a MATLAB version and an Octave version and a Python version.

Related Data and Programs:

doomsday_test

calendar_nyt, a MATLAB code which shows the correspondence between dates and the New York Times volume and issue number;

calpak, a MATLAB code which makes various calendar calculations;

dates, a dataset directory which contains lists of dates in various calendar systems.

weekday, a MATLAB code which determines the day of the week for a given day.

weekday_zeller, a MATLAB code which uses Zeller's congruence to determine the day of the week corresponding to a given date, such as 13 July 1989, Gregorian calendar, ... which was a Thursday.

Reference:

1. Lewis Carroll (Charles Dodgson),
   To Find the Day of the Week for Any Given Date,
   Nature, 31 March 1887.
2. John Conway,
   Tomorrow is the Day After Doomsday,
   Eureka,
   Volume 36, October 1973, pages 28-31.
3. Gary Meisters,
   Lewis Carroll's Day-of-the-Week Algorithm,
   Math Horizons,
   November 2002, pages 24-25.

Source Code:

• doomsday_gregorian.m, weekday given any date in Gregorian calendar.
• i4_modp.m, returns the nonnegative remainder of I4 division.
• i4_wrap.m, forces an I4 to lie between given limits by wrapping.
• weekday_to_name_common.m, returns the name of a Common weekday.
• weekday_values.m, returns the day of the week for various dates.
• year_is_leap_gregorian.m, returns TRUE if the Gregorian year was a leap year.