R.QWEIBULL 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.QWEIBULL returns a Weibull cutoff. With lower-tail probability p, its ordinary formula is scale×(−LN(1−p))^(1/shape). Upper-tail mode takes a survival probability instead; log_p means the supplied probability is already logarithmic. Versioned function help.

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

Probability, shape and scale are required, with positive shape and scale. lower_tail defaults to TRUE and log_p to FALSE. Use an ordinary probability from 0 through 1, or a nonpositive log probability with log_p=TRUE.

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

These self-contained formulas were recalculated natively. Ordinary-domain results were checked against independent mathematics; source guards explain the boundary cases. Results are rounded to twelve decimal places, or thirteen significant digits for small nonzero values. This is presentation precision, not a universal accuracy guarantee.

For shape 2 and scale 3, the median is approximately 2.497663833473. The 90th-percentile cutoff is approximately 4.552281388155. An upper-tail probability of 0.1 and its logarithmic form produce the same cutoff.

A stated target such as “90% of values are below this threshold” corresponds to a lower probability of 0.9. It does not mean entering 90 or using an upper probability of 0.9. Keep the percentage display separate from the decimal formula input.

The executed roundtrip below evaluates the lower CDF at the computed 90th percentile and recovers 0.9. Shape 1 reduces to an exponential quantile; for scale 2 the median is 2×LN(2), approximately 1.386294361120.

At fixed shape and probability, multiplying scale by a positive factor multiplies the quantile by the same factor. Shape changes the exponent and therefore the relative spacing of percentiles. This function does not estimate shape or scale from observations.

The saved advanced-check result for =R.PWEIBULL(R.QWEIBULL(.9,2,3),2,3) was 0.9.

Lower probability zero returns zero. Lower probability one has an infinite cutoff and becomes #NUM!; upper endpoints reverse those results. In log mode, input zero represents probability one and reaches that infinite lower endpoint. A positive log probability is invalid.

The helper checks positive shape and scale before its probability-boundary shortcut, so zero probability does not rescue a zero shape. Nonnumeric text gives #VALUE!; empty F5 becomes ordinary probability zero. Missing or extra arguments give #N/A. Infinite support limits are mathematical endpoints, not finite thresholds.

F5 is genuinely empty, rather than a cell containing an empty string.

• Current worksheet callback
• Tested-version worksheet callback
• Current qweibull calculation
• Tested-version qweibull calculation
• Nonfinite worksheet-value handling
• Statistical Functions From R plugin declaration
• Quantile boundary convention

The relevant complete worksheet callback and main calculation helper are unchanged between the inspected versions. That does not establish later-version numerical execution. Both stale and uncached SUM controls recalculated correctly. Native XML preserves the R.* identities. The secondary ODF export keeps these calls in the ORG.GNUMERIC namespace; it does not establish execution in another product. GUI entry, other locales and other spreadsheet products were not tested.

R.QEXP, WEIBULL, LN.