{ "category": "Compatibility", "display_name": "TDIST", "entry_kind": "built_in_function", "eval_api": { "method": "POST", "url": "https://handbook.dnacalc.com/api/eval" }, "function_id": "FUNC.TDIST", "implementation_state": { "answer_bank": { "excel_builds": [ "20131", "?" ], "larger_numeric": 2, "last_bit": 66, "matched": 24, "other_mismatch": 0, "refused": 0, "rows": 92, "unread": 0, "worst_ulp": 24 }, "detail": "Of 97 recorded answers (92 in the answer bank and 5 workbook cells), 70 do not match: 2 differ by more than 16 ULP, 68 differ by at most 16 ULP.", "dnacalc_commit": "9e1884369a678158dd82d3d74188daf986995e87", "in_catalogue": true, "state": "differs", "state_label": "Known larger differences", "summary": "Known larger differences on 70 of 97 recorded answers", "workbook_corpus": { "cells": 5, "last_bit": 2, "matched": 3, "worst_ulp": 11 } }, "implementations": [ { "commit": "9e1884369a678158dd82d3d74188daf986995e87", "flavour": "excel-compatibility-candidate", "language": "Rust", "name": "CalcFunc", "own_code": [ "https://github.com/DnaCalc/DnaCalc/blob/9e1884369a678158dd82d3d74188daf986995e87/crates/calc-func/src/catalogue/distributions.rs#L174-L184" ], "repository": "https://github.com/DnaCalc/DnaCalc", "shared_code": [ "catalogue/distributions::nums", "ported/chi_f_t_family::truncate_positive_integer", "ported/chi_f_t_family::validate_nonnegative_x", "ported/chi_f_t_family::t_dist_rt_kernel", "ported/chi_f_t_family::t_dist_2t_kernel", "ported/excel_numeric::binary_with", "ported/excel_numeric::excel_x87_add", "ported/excel_numeric::excel_x87_mul", "ported/excel_numeric::excel_x87_mul_add", "ported/excel_numeric/x87::mul", "ported/excel_numeric/x87::add", "ported/special_math_common::bratio_ftoi", "ported/special_math_common::bratio_spmpar1", "ported/special_math_common::bratio_exparg", "ported/special_math_common::bratio_esum", "ported/special_math_common::bratio_esum20", "ported/special_math_common::bratio_alnrel", "ported/special_math_common::bratio_rlog1", "ported/special_math_common::bratio_gam1", "ported/special_math_common::bratio_gamln1", "ported/special_math_common::bratio_gamln", "ported/special_math_common::bratio_algdiv", "ported/special_math_common::bratio_bcorr", "ported/special_math_common::bratio_gsumln", "ported/special_math_common::bratio_betaln", "ported/special_math_common::bratio_betaln_60", "ported/special_math_common::bratio_erf_nswc", "ported/special_math_common::bratio_erfc1", "ported/special_math_common::bratio_rexp", "ported/special_math_common::bratio_psi", "ported/special_math_common::bratio_fpser", "ported/special_math_common::bratio_apser", "ported/special_math_common::bratio_bpser", "ported/special_math_common::bratio_bup", "ported/special_math_common::bratio_brcomp", "ported/special_math_common::bratio_brcmp1", "ported/special_math_common::bratio_bfrac", "ported/special_math_common::bratio_bgrat", "ported/special_math_common::bratio_grat1", "ported/special_math_common::bratio_basym", "ported/special_math_common::bratio" ], "source": "https://github.com/DnaCalc/DnaCalc/blob/9e1884369a678158dd82d3d74188daf986995e87/crates/calc-func/src/catalogue/distributions.rs#L174-L184", "state": "differs", "suite": null, "summary": "Known larger differences on 70 of 97 recorded answers" } ], "json_url": "https://handbook.dnacalc.com/api/functions/FUNC.TDIST.json", "name": "TDIST", "notes": [], "schema": "efh.function-reference/v1", "section_order": [ "what-it-does", "try-it", "quirks", "how-to-implement", "version-differences", "alternatives" ], "sections": { "alternatives": "\n[T.DIST.RT](FUNC.T.DIST.RT.md) and [T.DIST.2T](FUNC.T.DIST.2T.md) make the tail explicit; [T.DIST](FUNC.T.DIST.md) provides a signed CDF/density; [TINV](FUNC.TINV.md) finds a two-tail critical value.\n\n\n", "how-to-implement": "\nFor nonnegative x and degree v, form `t2=x*x`, `den=v+t2`, and the paired beta arguments `z=v/den`, `zc=t2/den`. The current two-tail route evaluates the beta ratio with shape `v/2` and `1/2` using both supplied arguments; the one-tail route halves that result. Computing `zc=1-z` can lose an observed rounding. At x=v=1 both beta arguments are one half and the two-tail result is one half. Inner beta-ratio last bits remain open.\n\n\n", "quirks": "\nDegrees of freedom and tails are truncated. Degrees below one, negative x and tails other than one or two give `#NUM!`; nonnumeric inputs give `#VALUE!`. Halving or doubling a tail is a different operation from changing a CDF into an upper tail.\n\n\n", "sources": "\n- [Microsoft: TDIST function](https://support.microsoft.com/en-us/excel/functions/tdist-function), opened 6 November 2026; syntax, documented argument rules and errors.\n- [DnaCalc implementation](https://github.com/DnaCalc/DnaCalc/blob/da3ecc4fb19a3a5529708c311d0e8f05688ac165/crates/calc-func/src/ported/chi_f_t_family.rs); implementation steps and the limits identified in the text.\n\n", "try-it": "\n`=TDIST(1,1,2)` is about `0.5`; with one tail it is about `0.25`. At one degree of freedom the distribution is Cauchy, giving this useful control.\n\n\n", "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.\n\n| Excel 16.0 build | Platform and CPU | Captured inputs |\n|---|---|---:|\n| 19929 | Windows, bitness not recorded, CPU not recorded | 17 |\n| 20131 | Windows, bitness not recorded, AMD Ryzen 7 4800H with Radeon Graphics | 92 |\n\nThe 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.\n\n[Recorded environments and comparison details](https://github.com/DnaCalc/ExcelFunctionsHandbook/blob/5dc75391aa5125ccc5abdb095da85950980d6fd8/content/evidence/environments/FUNC.TDIST.json).", "what-it-does": "\n`TDIST(x,deg_freedom,tails)` returns a Student-t upper-tail probability. One tail means `P(T>x)`; two means `P(abs(T)>x)`. The compatibility function takes nonnegative x, not a signed cumulative-probability argument.\n\n\n" }, "signature": { "display": "TDIST(x, deg_freedom, tails)", "parameters": [ { "description": null, "name": "x", "optional": false, "repeats": false }, { "description": null, "name": "deg_freedom", "optional": false, "repeats": false }, { "description": null, "name": "tails", "optional": false, "repeats": false } ], "trailing_repeats": false }, "sources": { "metadata": { "admission": { "label": "implemented", "reason": null }, "arity": { "max": 3, "min": 3 }, "category": "Compatibility", "classification": { "arg_preparation_profile": "ValuesOnlyPreAdapter", "coercion_lift_profile": "Custom", "determinism_class": "Deterministic", "error_collapse_profile": "None", "fec_dependency_profile": "None", "host_interaction_class": "None", "kernel_signature_class": "Custom", "rich_value_usage": "RichBlind", "surface_fec_dependency_profile": "RefOnly", "thread_safety_class": "SafePure", "volatility_class": "NonVolatile" }, "descriptions": { "long": null, "short": "Student's t probability, one- or two-tailed (older form)", "short_source": "dna-calc-own" }, "docs": { "english_description": "Returns the Student's t-distribution", "microsoft_url": "https://support.microsoft.com/en-us/office/tdist-function-630a7695-4021-4853-9468-4a1f9dcdd192" }, "entry_kind": "built_in_function", "localized_family_names": null, "localized_names": [ { "locale": "ar-SA", "name": "TDIST" }, { "locale": "bg-BG", "name": "TDIST" }, { "locale": "cs-CZ", "name": "TDIST" }, { "locale": "da-DK", "name": "TFORDELING" }, { "locale": "de-DE", "name": "TDIST" }, { "locale": "el-GR", "name": "TDIST" }, { "locale": "en-AU", "name": "TDIST" }, { "locale": "en-GB", "name": "TDIST" }, { "locale": "en-US", "name": "TDIST" }, { "locale": "es-ES", "name": "DISTR.T" }, { "locale": "et-EE", "name": "TDIST" }, { "locale": "fi-FI", "name": "TJAKAUMA" }, { "locale": "fr-FR", "name": "LOI.STUDENT*" }, { "locale": "he-IL", "name": "TDIST" }, { "locale": "hr-HR", "name": "TDIST" }, { "locale": "hu-HU", "name": "T.ELOSZLÁS" }, { "locale": "id-ID", "name": "TDIST" }, { "locale": "it-IT", "name": "TDIST" }, { "locale": "ja-JP", "name": "TDIST" }, { "locale": "ko-KR", "name": "TDIST" }, { "locale": "lt-LT", "name": "TDIST" }, { "locale": "lv-LV", "name": "TDIST" }, { "locale": "nb-NO", "name": "TFORDELING" }, { "locale": "nl-NL", "name": "T.VERD" }, { "locale": "pl-PL", "name": "ROZKŁAD.T" }, { "locale": "pt-BR", "name": "TDIST" }, { "locale": "pt-PT", "name": "DISTT" }, { "locale": "ro-RO", "name": "TDIST" }, { "locale": "ru-RU", "name": "СТЬЮДРАСП" }, { "locale": "sk-SK", "name": "TDIST" }, { "locale": "sl-SI", "name": "TDIST" }, { "locale": "sr-Latn-RS", "name": "TDIST" }, { "locale": "sv-SE", "name": "TFÖRD" }, { "locale": "th-TH", "name": "TDIST" }, { "locale": "tr-TR", "name": "TDAĞ işlevi" }, { "locale": "uk-UA", "name": "TDIST" }, { "locale": "vi-VN", "name": "TDIST" }, { "locale": "zh-CN", "name": "TDIST" }, { "locale": "zh-HK", "name": "TDIST" }, { "locale": "zh-TW", "name": "TDIST" } ], "signature": { "display": "TDIST(x, deg_freedom, tails)", "parameters": [ { "description": null, "name": "x", "optional": false, "repeats": false }, { "description": null, "name": "deg_freedom", "optional": false, "repeats": false }, { "description": null, "name": "tails", "optional": false, "repeats": false } ], "trailing_repeats": false }, "surface_name": "TDIST", "version_marker": null, "xlcall": { "code": "301", "symbol": "xlfTdist" } }, "microsoft": "https://support.microsoft.com/en-us/office/tdist-function-630a7695-4021-4853-9468-4a1f9dcdd192" }, "try_it": { "formula": "=TDIST(1,1,2)" }, "url": "https://handbook.dnacalc.com/functions/TDIST.html", "variants": [], "versions": [ { "behaviour": "17 captured inputs are indexed for this environment. Capture dates are not recorded. This is a reading count, not a comparison with another build.", "excel_build": "16.0 build 19929", "platform": "Windows, bitness not recorded, CPU not recorded", "sources": [ "https://github.com/DnaCalc/ExcelFunctionsHandbook/blob/5dc75391aa5125ccc5abdb095da85950980d6fd8/content/evidence/environments/FUNC.TDIST.json" ] }, { "behaviour": "92 captured inputs are indexed for this environment. Capture dates: 2026-07-16 to 2026-07-17. This is a reading count, not a comparison with another build.", "excel_build": "16.0 build 20131", "platform": "Windows, bitness not recorded, AMD Ryzen 7 4800H with Radeon Graphics", "sources": [ "https://github.com/DnaCalc/ExcelFunctionsHandbook/blob/5dc75391aa5125ccc5abdb095da85950980d6fd8/content/evidence/environments/FUNC.TDIST.json" ] } ] }