FDIST Function (Gnumeric)

• Introduced: Gnumeric 0.25, explicitly listed among the new functions in its release notes.
• Availability: Supported in Gnumeric 1.12.62 according to its function-specific registration. No retirement endpoint is established.
• Scope: Desktop Gnumeric with the fn-stat module enabled. Examples use English comma-separated formulas.
• Checked: October 14, 2026. Reference and boundary tables were recalculated by Gnumeric 1.12.57 and checked independently. The 1.12.62 contract was source-checked, not executed.

For x≥0, the survival probability can be expressed as I_z(d2/2,d1/2), where z=d2/(d2+d1×x). This beta-integral relationship describes the upper tail directly. The F distribution is asymmetric, so a familiar normal-tail intuition is not a substitute for the correct model. Official FDIST reference.

=FDIST(x,dof_of_num,dof_of_denom)

All arguments shown are required. Use numeric cells or numeric inputs. The formulas use decimal points and commas; localized entry conventions require separate checks. Gnumeric 1.12.62 help and evaluator.

Enter each formula in a separate cell. The displayed references are rounded to twelve decimal places and agree with the recorded Gnumeric 1.12.57 recalculation within ordinary floating-point precision. Keep the stored result for subsequent calculations.

Suppose a statistic has F=2 with numerator and denominator degrees of freedom both 5. Put these inputs in A2:C2 and enter =FDIST(A2,B2,C2). The table gives the upper-tail probability. It is not the probability below 2.

For a ratio of sample variances, pre-specify which sample is the numerator and which is the denominator. With sample sizes n1 and n2, their usual degrees of freedom are n1−1 and n2−1 under the independent normal-sample model. Reordering the ratio after looking at the values changes the event being tested.

Check the reciprocal relationship

If F has degrees of freedom(d1,d2), then 1/F has the reversed pair(d2,d1). Accordingly =FDIST(2,2,4)+FDIST(0.5,4,2) is 1 for positive thresholds. This is a useful orientation check; swapping only the degrees of freedom while leaving x unchanged is different.

A one-sided 5% cutoff is =FINV(0.05,5,5). Feeding it back into FDIST with the same degrees of freedom should recover 0.05. For a two-sided variance question, determine both tails and their probability allocation before constructing the decision rule.

All three arguments are required. The wrapper rejects negative x and degrees of freedom below 1 after flooring. At x=0 the upper-tail probability is 1. Degrees of freedom are floored, not continuously parameterized in this worksheet wrapper. A matching function name in another program does not establish the same negative-input or coercion rules.

The following are observed cell results from the same 1.12.57 command-line recalculation. F5 was genuinely empty. A blank is not necessarily an omitted argument or a valid observation, so validate required data instead of treating every defaulted zero as intentional.

The fixtures do not certify every locale, extreme tail, imported type or newer binary build. The current wrapper agrees with the documented argument contract; shared numerical helpers can change between releases.

• FINV
• FTEST
• FDIST official manual entry
• Version-pinned argument contract and calculation