ISLOGICAL in Calligra Sheets: Spot Actual TRUE/FALSE Values

ISLOGICAL answers a precise question: is the evaluated value a Boolean, rather than just a number or text that looks like TRUE/FALSE? For a logical comparison such as =4>2, the expected predicate result is TRUE. For the number 1 or the text "TRUE", it is FALSE. The Calligra 26.08.2 callback directly tests args[0].isBoolean(). [E1–E4]

A status column imported from another system can contain genuine Boolean values, 1/0 flags and strings like TRUE. These appear similar on screen but are not the same type. Use this predicate as an audit before building conditional logic; it does not convert text into booleans. [E1–E3]

=ISLOGICAL(x)

x is the only required positional argument. The pinned XML types it Any, and declares the return type Boolean with no optional arguments or defaults. The implementation returns Value(args[0].isBoolean()) in information.cpp (registration near line 88, callback near lines 272–276). The quoted word "TRUE" is a string, not a Boolean literal. [E1–E3]

Open an empty worksheet and enter exactly the following values in column A; enter =ISLOGICAL(A2) in B2, then copy it down to B7. To enter a literal text string without automatic interpretation, use the quoted formula ="TRUE" rather than typing an unquoted label. [E1–E4]

Expected B2:B7: TRUE, TRUE, FALSE, FALSE, FALSE, FALSE. The two comparisons and the distinction between Boolean/text/number values follow the official definition and are independently reasoned. Classification of untouched references remains a native-test item rather than a measured Calligra output. [E1–E4]

Advanced example 1 — label a mixed flag column

In C2, enter and copy downward:

=IF(ISLOGICAL(A2);"Boolean flag";"Check type")

The predicted label for A2 and A3 is Boolean flag; the label for A4 to A6 is Check type. This is a type audit, not validation that TRUE is a business-approved status. A genuine FALSE is still a genuine Boolean. IF is a separately registered Calligra function; its interaction here is a source/documentation-based expectation, not a native test. [E1–E4]

Advanced example 2 — separate truth from validity

=IF(ISLOGICAL(A2);IF(A2;"Approved";"Rejected");"Unvalidated")

Enter the formula in D2 and copy it through D4. With A2==4>2, the expected result is Approved; with A3==2>4, Rejected; with A4=1, Unvalidated. This nested formula shows why merely converting nonzero numbers to TRUE can silently accept bad imports. Reproduce the first worksheet before testing this second example. [E1–E4]

Standalone controls

=ISLOGICAL(12) is an official documented FALSE example. =ISLOGICAL(1<2) predicts TRUE. =ISLOGICAL("FALSE") predicts FALSE because the quotation marks create text. [E1–E4]

• Text "TRUE" returns FALSE: the quotation marks make it a string. Correct upstream import typing rather than assuming text can be treated as a flag. [E1–E3]
• 1 returns FALSE: the value is numeric. Do not conflate a common database encoding of flags with worksheet Boolean type. [E3]
• A FALSE status still returns TRUE: ISLOGICAL tests the type, not whether the Boolean is TRUE. [E1, E3]
• A formula with a Boolean-looking display fails the check: inspect its actual resulting data type; cell formatting alone is not a type conversion. [E3]
• Blank and error-valued references: the callback checks isBoolean(); exact error propagation and blank coercion through the expression evaluator have not been executed. [E3, E4]
• Formula text and separators: a user entering "TRUE" without a formula or explicit text formatting might see different auto-entry behavior. For repeatability, use the explicit ="TRUE" formula and KDE’s documented syntax. [E1, E2]

Excel officially documents ISLOGICAL(value) and returns TRUE for Boolean values but not the quoted text "TRUE"; LibreOffice’s help likewise describes Boolean type testing. This is a named/semantic match on the tested cases, not proof of identical import coercion across installed versions. Microsoft examples sometimes display commas in multi-argument formulas, whereas the Calligra English handbook uses semicolons. Re-evaluate representative rows after migrating a workbook. [E1, E5]

Does ISLOGICAL tell me whether the condition is true? No. It returns TRUE for both genuine TRUE and genuine FALSE inputs; use the value itself after type checking. [E1, E3]

Does it convert zero/one into false/true? No. It identifies the evaluated input type; conversion is a different operation. [E3]

Is a checkbox automatically a Boolean? Depends on how a specific import or cell control stores its value; this was not tested, so inspect the actual output before assuming. [E4]

Calligra’s English reference uses a leading = for worksheet entry and a semicolon between arguments when a function needs several inputs. This function has one required argument, so its own syntax has no separator. The IF examples use ;; if your localized Calligra input configuration differs, use Insert → Function to verify separator entry. A displayed Boolean label or error message may be localized; compare the actual value category rather than translating a displayed error string. [E1, E2]

The implementation examined is the Calligra 26.08.2 function module at pinned commit 72123cc643f6625351139e7df294544255a1056f, associated with the 2026-10-08 release. The stable KF6 English handbook is an official description, not a log of this binary running on Linux, Windows or another platform. Calligra’s current KDE application page advertises a Linux install route; package availability and optional downstream patches can change. No installed Calligra application was available for native verification. [E1–E3, E6]

Validation taxonomy: DOC means an official handbook/XML statement; SOURCE means code inspected at the pinned revision; CALC means an independent truth-table or arithmetic check; EXPECTED means a predicted worksheet result. None of the displayed answers in these guides is a NATIVE_OBSERVED result. Recheck type-coercion, error propagation and localized displays before production use. [E1–E4]

• [E1 — KDE DOC] Official English Calligra Sheets function handbook, Information section for this named function and NA; accessed 2026-10-12. Official syntax, category and meanings.
• [E2 — KDE VERSION-PINNED XML] Calligra information.xml at 72123cc643f6, the exact <Function> entry. One Any argument, Boolean result and no declared optional parameter/default for this function; accessed 2026-10-12.
• [E3 — KDE VERSION-PINNED SOURCE] Calligra information.cpp at 72123cc643f6; corresponding Function registration and callback. Implementation observed in source, not a native run; accessed 2026-10-12.
• [E4 — INDEPENDENT LOGIC] The explicit input-type/error-category truth table shown above. Results calculated from Boolean predicates and documented error categories; not executed in Calligra.
• [E5 — COMPATIBILITY DOCS] Microsoft Excel IS functions and LibreOffice Calc information functions, both official vendor documentation, accessed 2026-10-12. Cross-product names and high-level meaning, not proof of identical parser/locale/runtime handling.
• [E6 — OFFICIAL RELEASE] KDE’s Calligra Sheets release listing, version 26.08.2 — October 8, 2026; accessed 2026-10-12.