R.PGEOM 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.PGEOM evaluates the cumulative probability of no more than x failures before the first success. For a nonnegative integer cutoff k, the lower tail is 1−(1−p)^(k+1), and the strict upper tail is (1−p)^(k+1). Versioned function help.

=R.PGEOM(cutoff,success_probability[,lower_tail[,log_p]])

• cutoff: required failure-count threshold; ordinary nonnegative fractional cutoffs are floored.
• success_probability: required chance on each independent trial, with 0<p≤1.
• lower_tail: optional TRUE for P(X≤x); FALSE for the strict upper tail P(X>x).
• log_p: optional FALSE. TRUE uses the natural logarithm of the probability.

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.

At p=0.2, R.PGEOM(3,0.2)=0.5904 is the chance of success within four attempts. R.PGEOM(3,0.2,FALSE())=0.4096 is the chance that all four attempts fail. Writing the event in attempts first helps avoid shifting the cutoff by one.

For at least three failures, use P(X>2), or R.PGEOM(2,0.2,FALSE()), which equals 0.512. For two through four failures inclusive, subtract R.PGEOM(1,0.2) from R.PGEOM(4,0.2), giving 0.31232. The geometric model is memoryless: after several failures, the chance of surviving another m trials is still (1−p)^m, provided independent identical trials remain a reasonable model.

The saved advanced-check result for =R.PGEOM(3,.2)+R.PGEOM(3,.2,FALSE()) was 1.

The source floors the cutoff but requires 0<p≤1. A negative cutoff has lower-tail probability zero; requesting its logarithm produces #NUM!. With p=1, every nonnegative cutoff has lower tail 1 and upper tail 0, so the log-upper-tail result is also #NUM!. Do not infer that an error at a log-zero endpoint means the ordinary probability is undefined.

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

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

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.

GEOMDIST, R.PBINOM, NEGBINOMDIST.