TINV

What it does

TINV(probability, deg_freedom)

TINV(probability,deg_freedom) returns a nonnegative Student-t critical magnitude for a two-tailed probability. It is the compatibility name for the two-tail inverse.

Try it

=TINV(0.5,1) returns 1 under the current explicit Cauchy control. Half the one-degree distribution lies beyond plus or minus one.

Quirks

Degrees are truncated. Invalid degrees or probabilities give #NUM!; nonnumeric inputs give #VALUE!. The public page admits probability one in its range wording, while the current shared inverse requires 0<p<1. For a one-tail upper critical value use twice that tail probability in the two-tail inverse, within its admitted range.

How to implement

For degree one, the retained route is 1/TAN(PI()*p/2), with a separate exact p=0.5 return of one. For higher degrees the code currently brackets and inverts the decreasing two-tail beta-ratio probability. Public-composition readings support a sqrt(v*(1/BETA.INV(p,v/2,0.5)-1)) construction on their scope, but the current beta inverse still differs; the code therefore retains its generic inverse. Do not describe that unresolved composition as a shipped exact route.

Rust code

46 tinv "TINV" (2, 2) [V "probability", V "deg_freedom"] |s, a, sv| {
    let [p, df] = nums::<2>(s, a)?;
    out(s, cft::t_inv_2t_kernel(p, df))
}

No implementation has been published with a Handbook test suite for this function.

Version differences

The recorded environments below distinguish a reading from a same-input comparison. Counts describe captured inputs in each environment; overlapping captures and comparisons are not totals of unique worksheet calls.

The record contains no same-input comparison between these environments. Reading different inputs on different builds does not establish either a version change or cross-build agreement.

Recorded environments and comparison details.

Alternatives

T.INV.2T is the explicit two-tail name; T.INV is a signed left-CDF quantile; TDIST returns a tail probability.

Named variants

No named variants are recorded yet.