Define Anno Mundi #16

NEWS.md

@@ -1,8 +1,13 @@
 # era (development version)
 
-* New year units: sidereal, tropical, and anomalistic astronomic years #15
-* More precise epoch value for Hijri eras: `621.5394` instead of `622`.
-* More precise epoch value for Nowruz (Solar Hijri) eras: `621.2218` instead of `622`.
+* New eras:
+  * Anno Mundi (Hebrew calendar)
+* New year units:
+  * Sidereal, tropical, and anomalistic astronomic years #15
+  * Hebrew lunisolar years
+* Changes to existing eras:
+  * More precise epoch value for Hijri eras: `621.5394` instead of `622`.
+  * More precise epoch value for Nowruz (Solar Hijri) eras: `621.2218` instead of `622`.
 * `this_year()` now considers the current date, returns a floored integer (i.e. the actual current calendar year), and is vectorised over `era`.
 * Class constructors `era()` and `yr()` return a zero-length vector when called with no arguments (instead of an error), allowing them to be used as [prototypes](https://vctrs.r-lib.org/articles/type-size.html)
 * `era_yr` objects can be cast to character vectors (e.g. `as.character(yr(1, "BP"))`)

data-raw/era_table.R

@@ -9,6 +9,8 @@ library("usethis")
 hijra <- era:::frac_year(as.Date("622-07-16")) - 1
 # Hijra (Nowruz) <https://web.archive.org/web/20050311055900/http://wwwusr.obspm.fr/~heydari/divers/ir-cal-eng.html>
 nhijra <- era:::frac_year(as.Date("622-03-22")) - 1
+# Era Mundi
+mundi <- era:::frac_year(as.Date("1-10-6")) - 3762
 
 # Year units
 # Mostly from https://en.wikipedia.org/wiki/Year
@@ -17,6 +19,7 @@ julian <- era_year("Julian", 365.25)
 solar <- era_year("solar", 365.24219)
 islamic_lunar <- era_year("Islamic lunar", 354.36708)
 nowruz <- era_year("Nowruz", 365.2424) # https://web.archive.org/web/20050311055900/http://wwwusr.obspm.fr/~heydari/divers/ir-cal-eng.html
+hebrew <- era_year("Hebrew lunisolar", 365 + (24311/98496)) # http://individual.utoronto.ca/kalendis/hebrew/Hebrew-Possible-Weekdays-view.htm
 radiocarbon <- era_year("radiocarbon", NA)
 sidereal <- era_year("sidereal", 365.256363004)
 tropical <- era_year("tropical", 365.24219)
@@ -66,6 +69,8 @@ era_table <- tribble(
   "BH",        hijra,  "Before the Hijra",                      islamic_lunar,  1L,    -1,
   "SH",        nhijra, "Solar Hijri",                           nowruz,         1L,    1,
   "BSH",       nhijra, "Before Solar Hijri",                    nowruz,         1L,    -1,
+  # Jewish calendars
+  "AM",        mundi,  "Anno Mundi",                            hebrew,         1L,    1,
   # Historic calendars
   # Ancient calendars
   # Quirky calendars

inst/WORDLIST

@@ -1,3 +1,5 @@
+Anno
+Mundi
 Codecov
 Hijri
 Hijri’