R.PBINOM Function (Gnumeric)

• Introduced: First release not established; named in Gnumeric 1.12.2 release notes.
• 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.PBINOM returns P(X≤cutoff) for a binomial count. Upper-tail mode returns P(X>cutoff), which is a strict inequality. The cutoff can be fractional because a cumulative event can be evaluated between integers. Versioned function help.

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

• cutoff: real threshold; ordinary fractional cutoffs are floored to the included integer count.
• trials: nonnegative integer number of independent trials.
• success_probability: common trial probability in [0,1].
• lower_tail: optional TRUE for the lower cumulative probability; FALSE requests the upper tail.
• log_p: optional FALSE. TRUE uses natural-log probabilities, not base-10 logarithms.

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 n=5 and success probability 0.5, cutoff 2 returns 0.5. Cutoff 2.9 returns the same value because the event still includes only 0, 1 and 2 successes. The upper-tail call at 2 returns P(X≥3)=0.5.

For an inclusive event X≥k, use the upper tail at k−1, not k. An independent interval example is P(2≤X≤4)=P(X≤4)−P(X≤1)=0.78125 for this same distribution.

With n=10 and per-trial probability 0.4, the native lower probability at 4 is 0.6331032576. This differs from the probability of exactly four successes, which is 0.250822656. The cumulative function sums all included counts.

The lower and strict upper tails sum to one. Direct log mode takes the logarithm of the selected tail; for the half-probability example it returns −0.693147180560. Prefer the direct upper tail to subtracting from one when investigating small probabilities.

The saved advanced-check result for =R.PBINOM(2,5,.5)+R.PBINOM(2,5,.5,FALSE()) was 1.

Negative cutoffs return lower probability zero, and cutoffs at or above n return one. Valid p=0 or p=1 describe degenerate counts; n=0 is also supported. Genuine fractional trial counts, negative trials and success probabilities outside [0,1] give #NUM!.

Near-integer trials use the source tolerance and rounding, so 5.000000000000001 was accepted. This differs from the stricter trial check in R.QBINOM. Empty cutoff F5 acts as zero; nonnumeric text is #VALUE!; invalid argument count is #N/A. Logarithms of zero produce #NUM!.

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

• Current worksheet callback
• Tested-version worksheet callback
• Current pbinom calculation
• Tested-version pbinom calculation
• Nonfinite worksheet-value handling
• Statistical Functions From R plugin declaration
• Near-integer tolerance

The deliberate fractional count/trial probes also emitted noninteger-input calculation warnings. The saved logs retain them.

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.

BINOMDIST, BINOM.DIST.RANGE, CRITBINOM.