R.QEXP Function (Gnumeric)

• Introduced: First release not established; present in the retained 1.12.57 source.
• Supported in: Gnumeric 1.12.62; no retirement is established.
• Scope: Desktop Gnumeric with its Statistical Functions From R plugin. English comma-separated formulas are shown.
• Checked: October 14, 2026. Tables and the named advanced check use 1.12.57 ssconvert. Current 1.12.62 source was inspected; that release was not executed.

R.QEXP returns an exponential quantile. The default first argument is a lower-tail probability; lower_tail=FALSE makes it an upper-tail probability. With log_p=TRUE, the first argument is the natural logarithm of that probability. Versioned function help.

=R.QEXP(probability,scale[,lower_tail[,log_p]])

• probability: p or LN(p), according to log_p.
• scale: required; use positive scale for an ordinary exponential model.
• lower_tail: optional, defaults TRUE.
• log_p: optional, defaults FALSE.

Brackets mark optional arguments; do not type them. Current worksheet implementation.

These self-contained formulas were recalculated natively and checked against independent mathematics. Results are rounded to twelve decimal places, or thirteen significant digits for small nonzero values. This is presentation precision, not a universal accuracy guarantee.

With scale 2, the median is =R.QEXP(0.5,2) =2×LN(2)≈1.386294361120. The 90th percentile is approximately 4.605170185988, equivalently the cutoff with an upper probability of 0.1.

The upper-tail form =R.QEXP(0.1,2,FALSE()) avoids changing the tail by hand. For logarithmic input use =R.QEXP(LN(0.1),2,FALSE(),TRUE()). Each expression describes the same specified cutoff.

For lower-tail p, x=−scale×LN(1−p). For upper-tail p, x=−scale×LN(p). A lower p=0 therefore gives the finite support endpoint zero; an upper p=0 requires an infinite cutoff. These endpoint cases differ from the two infinite tails of a normal distribution.

The native =R.QEXP(-1000,2,FALSE(),TRUE()) gives 2000 directly. Exponentiating −1000 first can lose the positive probability to underflow, so retain the log representation. The executed R.PEXP/R.QEXP round trip at lower p=0.9 returns 0.9 within rounding.

The saved advanced-check result for =R.PEXP(R.QEXP(.9,2),2) was 0.9.

Lower p=1 and upper p=0 yield #NUM! for their infinite mathematical endpoints; lower p=0 and upper p=1 give zero. Ordinary p outside [0,1] or a positive log probability errors. Zero scale produces zero for the tested interior case, but should not be substituted for a positive-scale model. Negative scale errors.

F5 is genuinely empty, rather than a cell containing an empty string. #NUM! can represent an unrepresentable infinite mathematical endpoint as well as an invalid numeric domain; the distinctions above matter.

• Current worksheet callback
• Tested-version worksheet callback
• Current qexp calculation
• Nonfinite worksheet-value handling
• Statistical Functions From R plugin declaration

The relevant worksheet callback is unchanged between the inspected versions. That does not establish later-version numerical execution. Both stale and uncached SUM controls recalculated correctly. Native XML identities were checked; secondary ODF exports retain these functions with the ORG.GNUMERIC namespace. GUI entry, other locales and other spreadsheet products were not tested.

EXPONDIST, LN, EXP.