"Gregorian Calendar" calculates any date in agrrement to the rules stated by the Pope Gregory XIII, i.e. after
October 15th, 1582. The representation is made on a month basis. The selection of the month is performed through four toggle buttons by which the month, the year and the century can be changed.
A forward and a backward button allow an easy and fast change of the selection. If these two buttons are kept pressed the change is done automatically every 400 msec.
The calculation of the days of the week is done according to the Zeller's congruence algorithm; the determination of the date of Easter makes use of the Oudin's algorithm.
No particular requirements are necessary.
The application has been developed on a 320x480 device and not tested for different devices. Any feedback of this subject is welcome.