# fixed_julian: _Rata Die_ Conversion to and from Julian Years In aion: Archaeological Time Series

 fixed_julian R Documentation

## Rata Die Conversion to and from Julian Years

### Description

Convenient functions for conversion from and to rata die.

### Usage

fixed_from_julian(year, month, day)

fixed_to_julian(object)

### Arguments

 year A numeric vector of years. If month and day are missing, decimal years are expected. month A numeric vector of months. day A numeric vector of days. object A RataDie object (see fixed()).

### Value

• fixed_from_julian() returns a RataDie object.

• fixed_to_julian() returns a numeric vector of Julian years.

N. Frerebeau

### References

Reingold, E. M. and Dershowitz, N. (2018). Calendrical Calculations: The Ultimate Edition. Cambridge University Press. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1017/9781107415058")}.

Other fixed date tools: arithmetic, as_date(), as_decimal(), as_fixed(), as_year(), fixed(), fixed_gregorian, format(), pretty()

### Examples

## R 1.0.0
(y <- fixed(year = 2000, month = 02, day = 29, calendar = CE()))
as_date(y, calendar = CE())
as_year(y, calendar = CE())

## Create a vector of years BP (Gregorian)
## (every two years starting from 2000 BP)
(years <- seq(from = 2000, by = -2, length.out = 10))
## Convert years to rata die
(rd <- fixed(years, calendar = BP()))
## Convert back to Gregorian years BP
as_year(rd, calendar = BP())

## More convenient
(rd <- fixed_from_BP(years))
fixed_to_BP(rd)

aion documentation built on Sept. 11, 2024, 9:30 p.m.