doomsday

doomsday, an Octave 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 computer code and data files described and made available on this web page are 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

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

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.