doomsday

doomsday, a Fortran90 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

analemma, a Fortran90 code which evaluates the equation of time, a formula for the difference between the uniform 24 hour day and the actual position of the sun, based on a program by Brian Tung.

calendar_nyt, a Fortran90 code which shows the correspondence between dates and the New York Times volume and issue number;

calendar_rd, a C++ code which computes the representation of a given date in a number of calendrical systems, by Edward Reingold and Nachum Dershowitz

calpak, a Fortran90 code which makes various calendar calculations;

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

weekday, a Fortran90 code which determines the day of the week for a given day.

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.f90, the source code.
• doomsday.sh, compiles the source code.