BESSELK
Quirk foundCategory: Engineering · Last tested 2026-09-01
Real compatibility results for the BESSELK function: executed in Excel for the web, Google Sheets and LibreOffice Calc, with desktop Excel behavior from Microsoft’s official documentation (we do not run desktop Excel — Excel for the web is a different application and is executed separately). Syntax and links to that documentation are below.
Support matrix
| Engine | Documented | Live-tested | Verdict |
|---|---|---|---|
| Excel (desktop) | Yes | No — documented only | n/a |
| Excel for the web | — | Yes (recalc, 2026-09-01) | Supported, behaves as documented |
| Google Sheets | No | Yes (Drive import, 2026-08-31) | Unsupported (not recognized) |
| LibreOffice Calc | Yes | Yes (25.8.7.3, 2026-08-31) | Quirk found |
LibreOffice version history
We executed the same test cases under each LibreOffice release to show exactly when BESSELK’s support changed — not documentation claims, real results.
| LibreOffice version | Verdict | Tested |
|---|---|---|
| 24.2.0.3 | Quirk found | 2026-08-31 |
| 24.8.7.2 | Quirk found | 2026-08-31 |
| 25.2.0.3 | Quirk found | 2026-08-31 |
| 25.8.7.3 | Quirk found | 2026-08-31 |
Why isn't BESSELK working in LibreOffice?
BESSELK exists in LibreOffice 25.8.7.3, but it is not a drop-in match for
Excel — our executed tests found real behavioral differences (detailed in the test results on this
page). If a formula that works in Excel or Google Sheets misbehaves in LibreOffice, compare your usage
against the failing cases above before assuming your data is wrong.
Why isn’t BESSELK working in Google Sheets?
Google Sheets does not implement BESSELK: we imported the formula into
Sheets on 2026-08-31 and every case came back #NAME?
(unrecognized function). Sheets is a rolling service with no version to pin, so this is a
statement about the service on that date, and Google’s own
function list does not document it either. Rewrite the formula with a documented
Sheets equivalent — see the
Excel ↔ Sheets equivalents table.
Discovered quirks
-
=ROUND(BESSELK(1.5,1),8) on
Google Sheets returned
#NAME?, but the documented/expected
result is 0.2773878.
Provenance
Microsoft's page publishes this example's result as 0.277387804. Independently re-derived to 20 significant digits with mpmath: besselk(1, 1.5) = 0.27738780045684381609, so the correct 9-dp value is 0.277387800 and the page's trailing ...804 is off by 3.5e-09. Asserting at 8 dp (0.2773878) is the deepest precision at which the published figure and the true value agree; MISMATCH vs expected: expected 0.2773878, got '#NAME?'
-
=ROUND(BESSELK(1.5,1.4),8) on
Google Sheets returned
#NAME?, but the documented/expected
result is 0.2773878.
Provenance
Excel documents "If n is not an integer, it is truncated", so order 1.4 must behave exactly as order 1 and return the documented 0.2773878. Independently verified with mpmath: a genuine fractional-order besselk(1.4, 1.5) would be about 0.35394, so this case separates truncation from fractional-order evaluation; MISMATCH vs expected: expected 0.2773878, got '#NAME?'
-
=BESSELK(1.5,-1) on
Google Sheets returned
#NAME?, but the documented/expected
result is #NUM!.
Provenance
Excel documents: "If n < 0, BESSELK returns the #NUM! error value."; MISMATCH vs expected: expected '#NUM!', got '#NAME?'
-
=BESSELK("abc",1) on
Google Sheets returned
#NAME?, but the documented/expected
result is #VALUE!.
Provenance
Excel documents: "If x is nonnumeric, BESSELK returns the #VALUE! error value."; MISMATCH vs expected: expected '#VALUE!', got '#NAME?'
-
=BESSELK(1.5,-1) on
LibreOffice Calc returned
#VALUE!, but the documented/expected
result is #NUM!.
Provenance
Excel documents: "If n < 0, BESSELK returns the #NUM! error value."; MISMATCH vs expected: expected '#NUM!', got '#VALUE!'
Executed test cases
Excel for the web (executed 2026-09-01 via OneDrive recalculation)
These values come from Excel for the web, not from desktop Excel. They are two different implementations of the calculation engine, and this run measured only the web one: the corpus was uploaded to OneDrive as .xlsx, recalculated by Excel for the web on open, and downloaded again for readback. Excel for the web is a rolling service with no pinnable version, so the run is identified by its date. Where a value here disagrees with the Expected column — which is Microsoft’s documentation of the desktop product — we cannot tell you whether the web engine diverges from the desktop one or the documentation is wrong about both, because we do not run desktop Excel.
| Formula | Description | Result | Expected | Verdict |
|---|---|---|---|---|
| =ROUND(BESSELK(1.5,1),8) | Microsoft's documented worked example: modified Bessel function K at x=1.5, order 1 | 0.2773878 | 0.2773878ProvenanceMicrosoft's page publishes this example's result as 0.277387804. Independently re-derived to 20 significant digits with mpmath: besselk(1, 1.5) = 0.27738780045684381609, so the correct 9-dp value is 0.277387800 and the page's trailing ...804 is off by 3.5e-09. Asserting at 8 dp (0.2773878) is the deepest precision at which the published figure and the true value agree |
Matched |
| =ROUND(BESSELK(1.5,1.4),8) | A non-integer order, which the documentation says is truncated toward zero | 0.2773878 | 0.2773878ProvenanceExcel documents "If n is not an integer, it is truncated", so order 1.4 must behave exactly as order 1 and return the documented 0.2773878. Independently verified with mpmath: a genuine fractional-order besselk(1.4, 1.5) would be about 0.35394, so this case separates truncation from fractional-order evaluation |
Matched |
| =BESSELK(1.5,-1) | A negative order | #NUM! | #NUM!ProvenanceExcel documents: "If n < 0, BESSELK returns the #NUM! error value." |
Matched |
| =BESSELK("abc",1) | A non-numeric x argument | #VALUE! | #VALUE!ProvenanceExcel documents: "If x is nonnumeric, BESSELK returns the #VALUE! error value." |
Matched |
Google Sheets (executed 2026-08-31 via Drive import)
Google Sheets is a rolling service with no pinnable version, so this run is identified by its date. The corpus was imported to Drive as .xlsx, recalculated by Sheets, and exported back for readback.
| Formula | Description | Result | Expected | Verdict |
|---|---|---|---|---|
| =ROUND(BESSELK(1.5,1),8) | Microsoft's documented worked example: modified Bessel function K at x=1.5, order 1 | #NAME? | 0.2773878ProvenanceMicrosoft's page publishes this example's result as 0.277387804. Independently re-derived to 20 significant digits with mpmath: besselk(1, 1.5) = 0.27738780045684381609, so the correct 9-dp value is 0.277387800 and the page's trailing ...804 is off by 3.5e-09. Asserting at 8 dp (0.2773878) is the deepest precision at which the published figure and the true value agree |
Mismatch |
| =ROUND(BESSELK(1.5,1.4),8) | A non-integer order, which the documentation says is truncated toward zero | #NAME? | 0.2773878ProvenanceExcel documents "If n is not an integer, it is truncated", so order 1.4 must behave exactly as order 1 and return the documented 0.2773878. Independently verified with mpmath: a genuine fractional-order besselk(1.4, 1.5) would be about 0.35394, so this case separates truncation from fractional-order evaluation |
Mismatch |
| =BESSELK(1.5,-1) | A negative order | #NAME? | #NUM!ProvenanceExcel documents: "If n < 0, BESSELK returns the #NUM! error value." |
Mismatch |
| =BESSELK("abc",1) | A non-numeric x argument | #NAME? | #VALUE!ProvenanceExcel documents: "If x is nonnumeric, BESSELK returns the #VALUE! error value." |
Mismatch |
LibreOffice Calc 25.8.7.3 (tested 2026-08-31)
| Formula | Description | Result | Expected | Verdict |
|---|---|---|---|---|
| =ROUND(BESSELK(1.5,1),8) | Microsoft's documented worked example: modified Bessel function K at x=1.5, order 1 | 0.2773878 | 0.2773878ProvenanceMicrosoft's page publishes this example's result as 0.277387804. Independently re-derived to 20 significant digits with mpmath: besselk(1, 1.5) = 0.27738780045684381609, so the correct 9-dp value is 0.277387800 and the page's trailing ...804 is off by 3.5e-09. Asserting at 8 dp (0.2773878) is the deepest precision at which the published figure and the true value agree |
Matched |
| =ROUND(BESSELK(1.5,1.4),8) | A non-integer order, which the documentation says is truncated toward zero | 0.2773878 | 0.2773878ProvenanceExcel documents "If n is not an integer, it is truncated", so order 1.4 must behave exactly as order 1 and return the documented 0.2773878. Independently verified with mpmath: a genuine fractional-order besselk(1.4, 1.5) would be about 0.35394, so this case separates truncation from fractional-order evaluation |
Matched |
| =BESSELK(1.5,-1) | A negative order | #VALUE! | #NUM!ProvenanceExcel documents: "If n < 0, BESSELK returns the #NUM! error value." |
Mismatch |
| =BESSELK("abc",1) | A non-numeric x argument | #VALUE! | #VALUE!ProvenanceExcel documents: "If x is nonnumeric, BESSELK returns the #VALUE! error value." |
Matched |
Docs & syntax
- Excel (desktop): official documentation
- LibreOffice Calc: official documentation
Where BESSELK behaves differently
- When the documentation is wrong: 29 vendor doc defects found by execution
Independent derivation across 586 executed functions found 29 places where a vendor's own page is contradicted by its own inputs, its own table, or the live engine: 23 Microsoft, 5 Google, 1 LibreOffice. Includes T.INV.2T's doubly-wrong Remark, DISC's stale figure, ISDATE's page against the live engine, and RAWSUBTRACT's help against LibreOffice's own result.