The derivative of an answer at a large hyperbolic argument evaluates to NaN or loses its imaginary part
维护者通常 1 天内回复
还没有人认领这个 Issue。
评估
调研方向
Start by reproducing the derivative evaluation with the exact parameters and x from the issue, comparing it with the integrand at 50, 300, and 2000 digits. Trace the derivative evaluation path and identify which subexpression causes NaN or loses the imaginary component; the issue does not name a file or test. Done means the derivative agrees with the integrand at the reported large argument and at x = 2 across those precisions.
由索引模型根据 Issue 内容生成。
描述
Found while checking Rubi 6.1.5, row 94 (1/sqrt(a + i a sinh(c + d x))) for 2.6.0. The answer is right. The library's own numerical evaluation of its derivative is not, at large arguments.
With a, c, d = 21/10, 19/10, 17/10 and x = 227283/1250 (so t = c + d x ≈ 311), the true value of the derivative is r(1 − i) with r ≈ 2.0185e-68. That is what mpmath gives at dps 400, and what the library gives when it evaluates the integrand itself.
The derivative of the answer, Differentiate(x) then substituted with exact rationals and evaluated, gives:
| digits | value |
|---|---|
| 50 | NaN |
| 300 | 1.5329…, which is wrong in magnitude too |
| 2000 | 2.0185…e-68: the real part is right and the imaginary part −2.0185…e-68 i is missing |
The relative difference at 2000 digits is exactly −1/2 + i/2. At x = 2 all three precisions agree with the integrand to the last digit.
The derivative holds e^(±t/2) and e^(±t) beside a + i a sinh(t), so large cancellations are expected. Losing a whole component at 2000 digits is not explained by that, though, and NaN at 50 digits should have been "could not evaluate". I have not narrowed it to a single subexpression.
Because of this, the Rubi harness reports this row as wrong, and anything that checks an answer by evaluating would do the same.
🤖 Generated with Claude Code
- 主要语言
- C#
- 星标
- 831
- 派生
- 79
- 平均合并
- 1 小时 12 分钟
- 30 天内合并 PR
- 467
环境准备
- 没有 Dockerfile 或 Docker Compose 文件
- 没有 Pull Request 模板
- 阅读贡献指南
从这里开始
- 先读完整个 Issue，再读项目的贡献指南。
- 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
- Fork 仓库，在一个分支上完成修改。
- 提交 Pull Request，并在描述里引用这个 Issue 编号。
ASC-Community/AngouriMath 的其他 Issue
-
难度 5/5 一周以上 新手友好度 35/100
ASC-Community/AngouriMath#1945 · 1 条评论 ·
维护者通常 1 天内回复
-
难度 5/5 一周以上 新手友好度 30/100
ASC-Community/AngouriMath#1807 · 2 条评论 ·
维护者通常 1 天内回复
-
难度 5/5 一周以上 新手友好度 25/100
ASC-Community/AngouriMath#1692 ·
维护者通常 1 天内回复
-
难度 5/5 一周以上 新手友好度 30/100
ASC-Community/AngouriMath#1690 ·
维护者通常 1 天内回复
-
难度 4/5 3-5 天 新手友好度 48/100
ASC-Community/AngouriMath#1689 · 5 条评论 ·
维护者通常 1 天内回复
查看 ASC-Community/AngouriMath 的全部 Issue
相似的 Issue
-
难度 2/5 1-3 小时 新手友好度 66/100
-
[Bug]: Revit selector reads process ids 2000-2099 as years (flaky AgentClientTests.AYearOrAProcessIdSelectsTheHost)可能已有人在做 @Wurschdhaud 今天认领。 未关闭
难度 2/5 1-3 小时 新手友好度 83/100
pyrevitlabs/pyRevit#3817 ·
维护者通常 1 天内回复
-
bug effort:S P2
难度 2/5 1-3 小时 新手友好度 76/100
nightscout/nocturne#2449 ·
维护者通常 1 天内回复
-
audit:1 bug
难度 2/5 1-3 小时 新手友好度 76/100
NethermindEth/dotnet-libp2p#395 ·
维护者通常 1 天内回复
-
area: client bug
难度 2/5 1-3 小时 新手友好度 72/100
维护者通常 1 天内回复