LEGACYCHIINV 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.

LEGACYCHIINV searches for a chi-square cutoff whose LEGACYCHIDIST right-tail probability equals the input. It remains an active compatibility name. The numerical search inherits the forward callback’s approximation and domain behavior. Function-specific official reference.

=LEGACYCHIINV(probability;degreesFreedom)

Exactly two arguments are required. For reliable ordinary examples use 0<probability<1 and 1≤degreesFreedom<100000. Probability=1 has cutoff zero. The inverse wrapper permits degree 100000, but the forward callback excludes it; avoid that inconsistent boundary. 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 four degrees of freedom and right-tail probability 0.05, the cutoff is near 9.487729036633 in the tested engine; the separate mathematical reference is near 9.487729036781. The small difference belongs to the numerical method.

For two degrees of freedom the mathematical quantile is -2*LN(probability). At p=0.5 this gives 2×LN(2); at p=0.9 it gives a small positive cutoff. Larger right-tail probabilities correspond to smaller cutoffs.

The saved roundtrip sends LEGACYCHIINV(0.05;4) back into LEGACYCHIDIST with degree 4. It recovers approximately 0.05, showing consistency with the same forward implementation. A roundtrip can pass even when both functions share an approximation; the independent reference remains useful.

This is a right-tail inverse. A lower-tail percentile p requires a right-tail probability 1−p, away from the problematic endpoints.

The executed advanced check was:

=LEGACYCHIDIST(LEGACYCHIINV(.05;4);4)

Its engine result was 0.05.

The zero-probability native output 128 is a search/saturation observation, not an infinite endpoint. Nonnumeric probability text was converted to zero and followed that same path. The tested degree=100000 median returned 0 because the inverse and forward guards differ; it is not a valid median for that distribution.

Negative probability, probability>1 and degree<1 were rejected. Do not rely on a non-error result as validation. Keep the zero-probability and maximum-degree limitations scoped to this tested engine, while the same callback structure is documented in current source.

• Function-specific implementation
• Versioned implementation reference
• Inverse helper
• Legacy Chi Cdf helper
• Gamma Dist 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.

CHIDIST, LN.