Bug: both `erfcinv(2big"0.8")` and `erfcinv(2big(0.41))` do not terminate.

Open
  • Is something wrong?
#557 3 comments 0 reactions 0 assignees View on GitHub

@lrnv is already working on this.

Since Sep 22, 2026.

  • #1 by @lrnv — closed without merging
  • #558 by @lrnv — open
  • #559 by @devmotion — open

Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
64/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Active
Tech stack
julia
Domain
tooling

Research direction

Start by running the Julia reproducer with erfcinv(2big"0.8") and compare it with erfcinv(2big(0.8)). Trace the erfcinv implementation and its handling of exact 0.8 values; done means the exact-value call terminates and behaves consistently with the working call.

Written by the indexing model from the issue text.

Description

using SpecialFunctions

erfcinv(2big"0.8") # never terminates
erfcinv(2big(0.8)) # works fine

The algorithm seems to have an issue with the exact 0.8 value.

Dominant language
Julia
Stars
384
Forks
115
Avg merge
2d 9h
Merged PRs (30d)
2

Getting set up

This project ships no dev container, Dockerfile or contributing guide, so setting up is up to you: start from its README, and see our first-contribution guide for the general steps.

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

More from JuliaMath/SpecialFunctions.jl

All issues in JuliaMath/SpecialFunctions.jl

Similar issues

More Julia issues

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.