weekday, a C code which determines the day of the week corresponding to a given date.
The information on this web page is distributed under the MIT license.
weekday 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 C 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, by Brian Tung.
dates, a dataset directory which contains lists of dates in various calendar systems.
doomsday, a C 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.
test_values, a C code which supplies test values of various mathematical functions.