PHP Date Math Class: Perform operations with dates with long year range

This class can perform operations with dates with long year range.

It can perform several operations with dates that can be outside the range of 1970 and 2038.

Currently it can add a period to a date, calculate the age relatively to a given birth date, check if a date is valid, convert a date to the Julian calendar, get the date day of the month, week or year, calculate the difference between two dates, get the first day or the end day of the current, prior or next week, month, or year, compare dates and get the latest, etc..

datetime difference
calculate datetime difference