Specify the reduced-interval accuracy of trigonometric polynomials

オープン
#1,041 コメント 0 件 リアクション 0 件 担当者 0 名 GitHub で見る

メンテナーはふだん 1 日以内に返信

まだ誰も着手していません。

評価

難易度
4/5
見積もり時間
3〜5日
初心者へのやさしさ
38/100
issue の種類
機能追加
明瞭さ
おおむね明確
活発さ
活発

調査の方向性

Start with std/math/trig.wave:69, the reported small-angle probes, and the related large-angle work in #600. Before changing code, discuss the proposed absolute, relative, and ULP contract with @LunaStev, including behavior near zeros and poles. Done means the bounds are agreed, independent high-precision fixtures cover interval and quadrant boundaries, the reduced-interval approximation meets the contract, and the #600 regressions plus separate f32 wrapper checks still pass.

索引モデルが issue の本文から書いたものです。

説明

discussion enhancement help wanted

Motivation

Small-angle testing avoids the large-angle reduction problem fixed in #600. At x=0.75, sin_f64 is 92 ULP from a 100-digit nearest reference; near pi/4 it is 184 ULP. cos differs by 4/10 ULP for those inputs. No correct-rounding contract is currently promised.

Starting point: std/math/trig.wave:69.

Validation

Audited canonical Wave 540728c2eb6cc12f5c69c3fb3fdb96e07ba059a4 (0.0.1-alpha-dev), whose tree matches the local checkout. Validation: Executed exact-bit small-angle probes and high-precision oracle; independent of huge-argument phase loss. Executed compiler probes use the matching checkout-built compiler and std on Linux amd64 (Rust 1.89.0 / LLVM 21.1.8). Source/header or mocked checks are not native execution on another OS.

Scope

Set an explicit error envelope for the reduced-interval sin/cos polynomial and resulting tan behavior. Improve the approximation only to meet that agreed goal; do not reopen the already replaced large-angle reduction algorithm as the same defect.

Related: #600. These links do not claim those broader or completed scopes are unfinished.

Design discussion required

This issue records a proposal or an unresolved contract; it is not approval to choose new semantics. Please mention @LunaStev to discuss the design before starting implementation.

Completion criteria

  • Define small/reduced-interval absolute/relative/ULP bounds and behavior near zeros/poles.
  • Use independent high-precision fixtures at interval/quadrant boundaries.
  • Retain #600 large-angle and non-finite regressions; verify f32 wrappers separately.
主要言語
Rust
スター
56
フォーク
21
平均マージ
20時間 49分
マージ済み PR(30日)
45

環境構築

はじめの一歩

  1. issue を最後まで読み、次にプロジェクトのコントリビューションガイドを読みます。
  2. 着手することを issue にコメントします — 二人が同じ作業をするのを防げます。
  3. リポジトリをフォークし、ブランチを切って変更します。
  4. issue 番号を参照したプルリクエストを送ります。

wavefnd/Wave のほかの issue

wavefnd/Wave の issue をすべて見る

似ている issue

Rust の issue をもっと見る

新しい issue をメールで受け取る

初心者向けの GitHub issue を短くまとめたダイジェスト。