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Module Cf_gregorian

module Cf_gregorian: sig .. end
Conversions between the Gregorian calendar and Chronological Julian Day.

Overview


This module implements functions for converting dates in the Gregorian calendar to and from a Chronological Julian Day (CJD) number. CJD numbers are signed integers, and day zero began at 00:00:00 TAI, 24 Nov -4713 CE.

Gregorian dates between 12 Aug -2937947 CE and 27 Feb 2935093 inclusive are convertible to Chronological Julian Day numbers on platforms where the Ocaml integer is a 31-bit integer.

Days of the month are represented by integers from 1 to 31. Months of the year are represented by integers from 1 to 12. Days of the week are represented by integers from 0 to 6, where 0 is Sunday and 6 is Saturday. Days of the year are numbered from 0 to 365, where only leap years contain a day numbered 365.

Functions

val is_valid : year:int -> month:int -> day:int -> bool
is_valid ~year ~month ~day returns true if year, month and day arguments specify a valid Gregorian date.
val of_cjd : ?wday:int Pervasives.ref ->
       ?yday:int Pervasives.ref -> int -> int * int * int
of_cjd ?wday ?yday cjd returns a 3-tuple (year, month, day) with the year, month and day of the corresponding Gregorian date represented in integer form.

If the ?wday parameter is used, then the day of the week is computed and stored. If the ?yday parameter is used, then the day of the year is computed and stored.

Raises Invalid_argument if cjd is in the very small range of values in the ancient past where the conversion algorithm would otherwise result in date in the extreme future.

val to_cjd : year:int -> month:int -> day:int -> int
to_cjd ~year ~month ~day returns the Chronological Julian Day number of the specified Gregorian date. Raise Invalid_argument if year, month or day indicates an invalid Gregorian date, or the calculation would overflow the integer representation of CJD numbers.
val to_cjd_unsafe : year:int -> month:int -> day:int -> int
to_cjd_unsafe ~year ~month ~day is the same as to_cjd ~year ~month ~day, except the parameters are not checked for boundaries and that the date is a valid Gregorian date. Use this version if the date is already known to be valid, and in the range of representable CJD numbers.