Calculates yahrzeit, the anniversary of a death, and returns it as a
SimpleHebrewDate ({yy, mm, dd}).
hyear must be after original date of death.
Returns undefined when requested year preceeds or is same as original year.
Hebcal uses the algorithm defined in "Calendrical Calculations"
by Edward M. Reingold and Nachum Dershowitz.
This is not the same calculation as a birthday. When the original
date does not exist in the target year, a yahrzeit falls earlier —
on the last day of the preceding month — because the anniversary
should not be observed later than the day itself. A birthday in the
same situation is postponed to the first of the following month.
See getBirthdayHD for the contrast.
The two also differ in whether the original year is a legal hyear.
A yahrzeit is by definition an anniversary of a death, so the
earliest one that exists is the first: the day of the death itself is
not a yahrzeit, and a "zeroth" yahrzeit has no meaning to return.
hyear must therefore be strictly after the year of death, and this
function returns undefined otherwise. A birth date, by contrast, is
a real and meaningful day in its own right, so
getBirthdayHD accepts the year of birth and hands back the
original date.
The customary anniversary date of a death is more complicated and depends
also on the character of the year in which the first anniversary occurs.
There are several cases:
If the date of death is Marcheshvan 30, the anniversary in general depends
on the first anniversary; if that first anniversary was not Marcheshvan 30,
use the day before Kislev 1.
If the date of death is Kislev 30, the anniversary in general again depends
on the first anniversary — if that was not Kislev 30, use the day before
Tevet 1.
If the date of death is Adar II, the anniversary is the same day in the
last month of the Hebrew year (Adar or Adar II).
If the date of death is Adar I 30, the anniversary in a Hebrew year that
is not a leap year (in which Adar only has 29 days) is the last day in
Shevat.
In all other cases, use the normal (that is, same month number) anniversary
of the date of death. [Calendrical Calculations p. 113]
The date argument is never modified, so a single original date can be
reused to generate a run of years.
Calculates yahrzeit, the anniversary of a death, and returns it as a
SimpleHebrewDate({yy, mm, dd}).hyearmust be after originaldateof death. Returnsundefinedwhen requested year preceeds or is same as original year.Hebcal uses the algorithm defined in "Calendrical Calculations" by Edward M. Reingold and Nachum Dershowitz.
This is not the same calculation as a birthday. When the original date does not exist in the target year, a yahrzeit falls earlier — on the last day of the preceding month — because the anniversary should not be observed later than the day itself. A birthday in the same situation is postponed to the first of the following month. See getBirthdayHD for the contrast.
The two also differ in whether the original year is a legal
hyear. A yahrzeit is by definition an anniversary of a death, so the earliest one that exists is the first: the day of the death itself is not a yahrzeit, and a "zeroth" yahrzeit has no meaning to return.hyearmust therefore be strictly after the year of death, and this function returnsundefinedotherwise. A birth date, by contrast, is a real and meaningful day in its own right, so getBirthdayHD accepts the year of birth and hands back the original date.The customary anniversary date of a death is more complicated and depends also on the character of the year in which the first anniversary occurs. There are several cases:
The
dateargument is never modified, so a single original date can be reused to generate a run of years.