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