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HDATE_DAY Function (Gnumeric)

Date & Time Beginner Gnumeric

Convert Gregorian date components to Hebrew day-of-month numbers in Gnumeric with HDATE_DAY, reproducible dates and current-date defaults.

Verification status: Gnumeric 1.12.57 ssconvert bounded HDATE-DAY fixtures only; retained 1.12.62 source inspected separately; no GUI. How formula examples are checked

HDATE_DAY converts a Gregorian calendar date into the day-of-month number in the Hebrew calendar. It returns a number such as 6, not a complete date string or a Gregorian day number. The function name contains an underscore even though this guide’s URL uses a hyphen.

Syntax and current-date defaults

=HDATE_DAY([year[,month[,day]]])

The arguments are Gregorian year, month and day components, in that order. Each omitted component defaults to the corresponding component of the computer’s current local civil date in the examined implementation. All three arguments may be supplied for a reproducible conversion; the zero-argument call uses the current date and is volatile.

Do not pass a spreadsheet date serial as the first argument and expect it to be decoded. If A1 holds a genuine spreadsheet date, use =HDATE_DAY(YEAR(A1),MONTH(A1),DAY(A1)). The function accepts date components, unlike functions whose single argument is a date value.

This is a calendar-date conversion. It does not calculate local sunset, take a geographic location or infer whether an event occurred before or after sunset. A religious observance or historical event near the evening boundary needs an appropriate date convention outside this function.

Worked example: a fixed Gregorian date

Enter =HDATE_DAY(2001,3,30) in an empty cell. The expected result is 6. The independently checked full conversion is 30 March 2001 = 6 Nisan 5761. HDATE_DAY supplies only the 6; it does not identify Nisan or 5761 in that result.

For another check, =HDATE_DAY(2024,10,3) returns 1, corresponding to 1 Tishrei 5785. =HDATE_DAY(2024,10,5) returns 3. These fixed dates make a more reliable teaching fixture than HDATE_DAY(), whose answer changes with the computer’s date.

The returned value should normally use a plain numeric format. Formatting it as a spreadsheet date could display a misleading date serial, because a day-of-month number is not a complete date.

Advanced use: convert a date column

Put =DATE(2024,10,3) in A1 and =DATE(2024,10,5) in A2. In B1 enter =HDATE_DAY(YEAR(A1),MONTH(A1),DAY(A1)) and copy to B2. The expected day numbers are 1 and 3. Keep the source date in column A; the day number alone repeats every month and is not a unique chronological key.

If you group events by Hebrew day-of-month, include the relevant month and year in the grouping design. Sorting only the day component would put all first days together rather than preserving chronological order. Likewise, subtracting two returned day numbers is not a general elapsed-days calculation across month boundaries; subtract the original valid date serials for ordinary civil-day differences.

Errors and input validation

  • Month 0 or 13 is outside the accepted component range and produced #VALUE! in the bounded fixture.
  • Supply valid Gregorian components deliberately. The underlying helper’s basic range checks do not establish that every impossible date, such as a month-specific invalid day, will be rejected uniformly.
  • Zero is not the same as omission. An omitted month uses the current month; an explicit zero month is invalid in the tested case.
  • Partial arguments mix fixed components with current-date components. A historical year with an omitted month and day is not a fully fixed historical date.
  • A fractional component is converted to an integer by the examined argument path. Use integers instead of depending on truncation.
  • The result has no timezone or sunset information. Do not treat it as a timestamp or a complete observance calendar.

History and verification

Official NEWS records the Hebrew calendar function group in Gnumeric 1.9.15. The individual callback and defaults were inspected in retained 1.12.62 source; that group milestone is not a claim of native testing in 1.9.15. Fixed-date expectations were independently checked with Hebcal’s published converter. Native fixture results are scoped separately below, and no retirement date is inferred.

DATE, YEAR, MONTH and DAY prepare Gregorian components from spreadsheet dates.

Independent calendar references

Official sources

Native verification scope

On 17 October 2026, Gnumeric 1.12.57 ssconvert recalculated 5 bounded HDATE_DAY fixture records in C.UTF-8. The recorded outputs matched the independent expectations described here. This is engine evidence, not GUI or screenshot evidence. Examples using composed helper formulas or affine transformations are mathematical checks unless separately recorded; other versions and untested boundaries remain outside this scope.