Chinese Calendrics Software 8.  Moving Forward and Backward

Chinese Calendrics allows adding or subtracting a time period to or from a date in one of these calendars, either by using the 'Move forward/back' facility or by using the 'Convert' facility with a value specified for the number of days.

The displayed date may be moved forward or backward by any of the following time periods:

 1 minute 1 hour 1 day 1 CE month 1 CE year 1 CE century 1 80-year cycle (Julian Calendar) 1 CHL month 1 CHL year 1 60-year cycle (Chinese Lunar Calendar) 1 CHS solar term 1 CHS year 1 60-year cycle (Chinese Solar Calendar) 1 60-day cycle

The 'Move' button is used to move the displayed dates forward or backward by any of the above periods; it does not require any content in the 'Date' box.

When a move of 80 years in the Julian Calendar is made the element-animal of the day does not change. This is because 80 years JC = 29,220 days = 487 60-day cycles.

The 'Convert' button is used (a) to convert a date in the 'Date' box to dates in the other calendars or (b) to add or subtract a specified number of days (which may include a fractional part) given in the 'plus/minus' box to or from a date in the 'Date' box.

If you click on 'Convert' with a value in the 'plus/minus' box, but with the 'Date' box empty, then the program will perform the addition or subtraction with the currently displayed date.

This allows moving in units of other cycles, such as the Metonic cycle, which consists of 235 synodic months. One synodic month = 29.530588 days, so 235 = 6939.688 days, so to add one metonic cycle add 6939.688 days. E.g., adding 6939.688 days to 79-21-06-01 CHL 19:24 CCT = 2004-07-17 CE 11:24 GMT gives 79-40-06-01 CHL 11:55 CCT = 2023-07-18 CE 03:55 GMT. Note that in the Chinese lunar dates both the month number and the day number are unchanged.