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Rata Die (Fixed Date)

## Usage

fixed(year, month, day, calendar, ...)

# S4 method for numeric,missing,missing,GregorianCalendar
fixed(year, calendar, scale = 1)

# S4 method for numeric,numeric,numeric,GregorianCalendar
fixed(year, month, day, calendar)

# S4 method for numeric,numeric,numeric,JulianCalendar
fixed(year, month, day, calendar)

## 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.

calendar

A TimeScale object specifying the calendar of year, month and day (see calendar()).

...

Currently not used.

scale

A length-one integer vector specifying the number of years represented by one unit. It should be a power of 10 (i.e. 1000 means ka).

## Value

A RataDie object.

## Details

Rata die are represented as the number of days since 01-01-01 (Gregorian), with negative values for earlier dates.

## References

Reingold, E. M. and Dershowitz, N. (2018). Calendrical Calculations: The Ultimate Edition. Cambridge University Press. doi:10.1017/9781107415058 .

## See also

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

N. Frerebeau

## Examples

## R 1.0.0
(y <- fixed(year = 2000, month = 02, day = 29, calendar = CE()))
#> Rata die: number of days since 01-01-01 (Gregorian).
#> [1] 730179
as_date(y, calendar = CE())
#>   year month day
#> 1 2000     2  29
as_year(y, calendar = CE())
#> [1] 2000.161

## Create a vector of years BP (Gregorian)
## (every two years starting from 2000 BP)
(years <- seq(from = 2000, by = -2, length.out = 10))
#>  [1] 2000 1998 1996 1994 1992 1990 1988 1986 1984 1982
## Convert years to rata die
(rd <- fixed(years, calendar = BP()))
#> Rata die: number of days since 01-01-01 (Gregorian).
#>  [1] -18627 -17897 -17166 -16436 -15705 -14975 -14244 -13514 -12783 -12053
## Convert back to Gregorian years BP
as_year(rd, calendar = BP())
#>  [1] 2000 1998 1996 1994 1992 1990 1988 1986 1984 1982

## More convenient
(rd <- fixed_from_BP(years))
#> Rata die: number of days since 01-01-01 (Gregorian).
#>  [1] -18627 -17897 -17166 -16436 -15705 -14975 -14244 -13514 -12783 -12053
fixed_to_BP(rd)
#>  [1] 2000 1998 1996 1994 1992 1990 1988 1986 1984 1982