TINV Function (Calligra Sheets)

• Introduced: First release not established; the name is present in Calligra 2.4.0 source.
• Supported in: Calligra Sheets 26.08.2, with no retirement established.
• Scope: Desktop Sheets with the Statistical module. Compatibility names remain registered; no retirement is inferred. Examples use English semicolon-separated formulas.
• Checked: October 14, 2026. Selected formulas ran through the official 25.04.2 engine library. Source and independent mathematics were checked. This is engine evidence, with no GUI-cell or import verification; 26.08.2 was source-checked only.

TINV returns a nonnegative Student t cutoff for a specified two-tailed probability. It inverts TDIST(x;degreesFreedom;2). The input is the probability outside −x and x, rather than the cumulative probability below x. Function-specific official reference.

=TINV(twoTailedProbability;degreesFreedom)

Exactly two arguments are required. Use 0<twoTailedProbability≤1 and 1≤degreesFreedom≤100000. Fractional degrees are retained. Probability=1 gives zero; exclude probability zero because of the observed numerical-search limitation. Registration and implementation.

The engine and mathematical columns are separate. Results are rounded to twelve decimal places, or thirteen significant digits in scientific notation for very small or large values. This is a display choice, not an accuracy guarantee.

For total tail probability 0.05 and 10 degrees of freedom, the engine gives approximately 2.228138851391. This is the positive cutoff for a central 95% interval under that t model. With one degree of freedom the corresponding cutoff is much larger, near 12.706204739516.

For an upper-tail probability q with 0<q≤0.5, supply total two-tail probability 2q to obtain the corresponding nonnegative cutoff. Do not supply 0.95 when you mean a central 95% interval.

The two-tail survival probability at x≥0 can be expressed through a regularized beta integral with argument ν/(ν+x²). The numerical inverse searches against the source’s TDIST helper.

The saved roundtrip returns TDIST(TINV(0.05;10);10;2), approximately 0.05. A fractional degree example at 2.5 confirms that the parameter is not automatically truncated. The independent references distinguish mathematical cutoffs from small source-approximation residuals.

The executed advanced check was:

=TDIST(TINV(.05;10);10;2)

Its engine result was 0.05.

The wrapper rejects probabilities below zero or above one and degrees below 1 or above 100000. It accepts p=0, where the iterative search terminates at a large finite value rather than infinity. Nonnumeric probability text became zero and followed that same path.

The tested degree=100000 interior result was finite. That differs from LEGACYCHIINV’s forward-guard mismatch and must not be generalized across inverse functions. Validate types and probabilities, and keep model-based inference separate from merely obtaining a numeric cutoff.

• Function-specific implementation
• Versioned implementation reference
• Inverse helper
• T Cdf helper
• Beta helper
• Conversion helper

The statistical and math modules and value-calculation helpers are byte-identical between the inspected 25.04.2 and 26.08.2 sources. That comparison supports the source discussion but does not establish later-version execution, GUI-cell behavior or other locales.

TDIST, CONFIDENCE, NORMSINV.