GAMMALN Function (Calligra Sheets)

• Introduced: First release not established; the name is present in Calligra 2.4.0 source.
• Supported in: Calligra Sheets 26.08.2, with no retirement established.
• Scope: Desktop Sheets with the Statistical module. Examples use English semicolon-separated formulas.
• Checked: October 14, 2026. Selected formulas ran through the official 25.04.2 engine library. Source and independent mathematics were checked. This is engine evidence, with no GUI-cell or import verification; 26.08.2 was source-checked only.

GAMMALN returns the natural logarithm of Gamma(x) for positive x. For a positive integer n, Gamma(n)=(n−1)!, so GAMMALN(5) corresponds to ln(24). It is not log base 10 and does not compute ln(n!). Function help.

=GAMMALN(x)

Exactly one argument is registered. The wrapper requires x>0. Noninteger positive values are supported. The tested numeric text “3” is converted to 3, TRUE becomes 1, and invalid text is rejected by the resulting domain check. Registration and implementation.

The engine and mathematical columns are separate. Results are rounded to twelve decimal places, or thirteen significant digits in scientific notation for very small or large values. This is a display choice, not an accuracy guarantee. NaN and infinity are nonfinite outputs; an engine error flag is checked separately from those values.

Products of positive gamma values can be handled in log space by adding their logarithms. For the simple factorial identity, GAMMALN(10) represents ln(9!), approximately 12.801827480081 in independent mathematics. The table preserves the separate engine value.

Do not assume that a negative log-gamma value is an error: Gamma(1.5) is less than 1, so its natural logarithm is approximately −0.120782237635. The domain concerns the input x, not the sign of the returned logarithm.

The recurrence Gamma(x+1)=x Gamma(x) implies logGamma(x+1)−logGamma(x)=ln(x) for x>0. Another check is the displayed GAMMALN(5)−LN(24), whose engine residual is about −1.80×10^−11.

Mathematically GAMMALN(1) and GAMMALN(2) are exactly zero. The tested engine returned approximately 1.05×10^−10 and 6.14×10^−11. Those small nonzero values follow the shared coefficient approximation and are deliberately not shown as exact zero. Avoid equality-to-zero tests built on this identity.

The executed advanced check was:

=GAMMALN(5)-LN(24)

Its engine result was -1.800368860071E-11.

The source uses a short fixed-coefficient gamma approximation. The number of printed decimals should not be read as a corresponding accuracy guarantee. Zero and negative inputs return #VALUE! rather than a reflected real log-gamma extension. A valid ordinary result also does not certify arbitrary large arguments or every cancellation-sensitive difference of log-gamma values.

• Function-specific implementation
• Versioned function help
• Loggamma helper
• Gamma approximation coefficients

The statistical module and value-calculation helpers are byte-identical between the inspected 25.04.2 and 26.08.2 sources. That comparison supports the source discussion but does not establish later-version native output, every locale or arbitrary extreme-parameter accuracy.

LN.