Use =ACOSH(5) to get the independently calculated 2.29243167 (shown to eight decimal places). ACOSH finds the nonnegative principal real value t for which COSH(t) equals the input x. The real-number input domain is x ≥ 1; at x = 1 the result is exactly 0. Below 1, no real result exists. The output shown here is a mathematically expected value, not an actual Calligra Sheets execution result.

=ACOSH(number)

The KDE handbook and the tagged Calligra 26.08.2 trig.xml declare ACOSH(Float) and show the expected =ACOSH(5) example. The associated trig.cpp registers ACOSH and calls calc->acosh(args[0]). This checks the one-argument implementation’s documented intent; it is not a test of a packaged Calligra binary. The 26.08.2 KDE Gear release was dated October 8, 2026 (announcement); sources were accessed 2026-10-11. A function’s presence in the handbook and source registry does not guarantee that a particular installed package enables the function or reproduces the same display formatting.

Domain and inverse-function distinction

The real-number input domain is x ≥ 1; at x = 1 the result is exactly 0. Below 1, no real result exists. The inverse hyperbolic function is not the ordinary inverse trigonometric function (for example, ACOS). Despite a generic “Angle (radians)” parameter label inherited from the older KDE handbook, the input is normally a dimensionless real number; the output is not an ordinary angle that should be converted to degrees. Do not insert RADIANS or DEGREES automatically.

Formula entry and locale details

Enter =ACOSH(A2) in the formula bar. Numbers such as 0.8 are written with a decimal point in this English-language example; your regional numeric conventions may require a comma. The KDE English function examples use semicolons between arguments for multi-argument functions, but this function has exactly one argument, so no separator is needed. If your installation localizes function names, use the function chooser; no native localized system or conversion was tested.

1. In a blank sheet, enter Numeric x into A1 and ACOSH(x) into B1.
2. Type the six numeric inputs into A2:A7, in the exact order below; these are numeric values, not quoted strings.
3. In B2, enter =ACOSH(A2) and fill/copy the formula through B7. The relative A2 reference must increment to A3, A4, etc.
4. Format column B to eight decimal places and compare within a small tolerance (for example 0.00000001 plus a sensible floating-point margin).

All displayed outputs were independently calculated using Python math.acosh and then rounded for presentation on 2026-10-11. They were not observed by running Calligra or importing a workbook. Hand-calculated identities and independently evaluated numerical examples complement documentation checking; they do not replace real spreadsheet validation. Displaying eight decimals does not alter underlying floating-point precision.

Cross-check with its paired hyperbolic function

The mathematical inverse relationship is COSH(ACOSH(x)) = x for x ≥ 1. =ACOSH(COSH(1)) is expected to return 1 within a floating-point tolerance. More generally, ACOSH(COSH(t)) = ABS(t) for real t because COSH(t) is even and ACOSH chooses a nonnegative principal value. Mathematically, ACOSH(x)=LN(x+SQRT(x^2-1)) for x ≥ 1; this is a useful derivation, but the direct formula may lose precision very near 1 or overflow intermediate squares for huge x. Use the built-in ACOSH for normal work.

For a model where a positive scale a multiplies hyperbolic cosine, y = a*COSH(t), solve for the nonnegative parameter t as ACOSH(y/a). Put the scale 2 in E2 and a target value 4 in F2. Enter =ACOSH(F2/E2) in G2; independently expect 1.31695790. Enter =E2*COSH(G2) in H2; the expected reconstructed target is approximately 4. The input constraints are E2 > 0 and F2/E2 ≥ 1. Because COSH is even, this inverse recovers the nonnegative t; negative t gives the same y, so do not claim unique sign recovery.

• Input below 1. The official handbook shows ACOSH(0) as NaN, indicating an invalid real input. The exact installed spreadsheet cell error/display has not been observed; avoid promising a particular error code.
• Close to 1. Small changes near 1 produce results sensitive to the input’s stored precision. If a computed ratio is mathematically 1 but stored as 0.999999999999, the function may reject it; check upstream arithmetic rather than silently clipping values.
• Negative parameter ambiguity. ACOSH is nonnegative. If you need to recover the sign of a parameter in COSH(t), additional information is required; COSH(t)=COSH(-t).
• Not inverse ordinary cosine. ACOS works on a different domain and returns a circular angle; ACOSH returns a hyperbolic inverse value and requires x ≥ 1.
• Unrecognized formula: Verify the function spelling, leading =, and that your installed package includes the trigonometry function module. A release registration is not proof of behavior in a particular installation.
• Text versus numeric data: Imported strings, numbers stored as text, and units such as "2 units" are not documented floating-point numeric arguments. Native coercion rules and resulting error strings have not been checked.
• Rounding and display: Check actual stored input cells and show more decimal places before assuming the function result is wrong. Round-trip identities should be compared with tolerance, not strict equality in every case.
• Regional settings: If the example formula appears as text or parses unexpectedly, check cell format, decimal conventions and localized formula entry. No locale-specific native test was run.

Excel also documents ACOSH(number) with a required real number at least 1; Calc documents a similarly named inverse hyperbolic cosine function. Names/domain agree in documentation, but native error mapping, precision, locale handling, data import and export have not been run or compared.

The comparison uses the official Microsoft Excel ACOSH help and LibreOffice Calc mathematical functions, accessed 2026-10-11; neither application was executed. Mathematical agreement does not establish identical parsing, coercion, domain errors, decimal formatting or workbook compatibility.

• Official COSH function reference — paired hyperbolic function, for checking the inverse identity.
• Official ACOSH function reference — exact signature and built-in examples.
• KDE Calligra 26.08.2 trigonometry descriptions and registered C++ implementation — released code, not native test output.
• KDE Gear 26.08.2 release and Calligra downloads — release/platform scope; Linux packages and Flatpak are recommended, while Windows support is listed as in progress.

These are checked official external documentation/source destinations. The proposed future internal tutorial slug is /calligra/functions/acosh/, but it has not been published or verified as a live page; do not assume the links are working internal pages.

• Calligra Sheets — function documentation
• 26.08.2 trig.xml
• KDE tagged trig.cpp
• announcement
• LibreOffice Calc mathematical functions
• Official COSH function reference

Verification status: Official documentation checked; example outcomes were independently reasoned or arithmetically checked where applicable. Not executed in Calligra Sheets.

• No genuine Calligra Sheets screenshots are included; this guide does not use mock application images.