[Rafael-SOWNet]

A factor tending to 0 times a sum tending to an infinity is asked term by term, from one side. Read as a product, l'Hôpital's rule took x (ln(-tanh(x)) + 1) at 0 from the left through four and a half seconds of nested limits, where x ln(-tanh(x)) + x is 0 at once. (tanh(x)^3)^exp(1/x) comes to the same product. #2385 slowed that row from 0.5 s to 7.5 s and accepted the slowdown, and this fixes it. The rewrite is exact, and it has the same gates as the quotient regroup in #2384: one side only, and not while the two sides of a limit are being compared. A term-by-term answer of NaN is not taken. The product is read as before.

Limit at 0, from the left	2.6.0	master	branch
x (ln(-tanh(x)) + 1)	0, 3.2 s	0, 4.5 s	0, 0.44 s
e^(1/x) (3 ln(-tanh(x)) + 1)	0, 1.0 s	0, 7.2 s	0, 0.46 s
(tanh(x)^3)^exp(1/x)	1, 0.5 s	1, 7.5 s	1, 0.47 s
sin(x) (ln(-tanh(x)) + 1/x)	1, 3.7 s	1, 5.2 s	1, 1.1 s

limitcheck A/B against master (DEPTH=3, the usual seeds): no answer lost. Five rows that timed out and five that were left unevaluated now finish. Two answers are new:

• log(pi, x)^sinh(x) sin(1) at 0, from each side, is sin(1). The exponent tends to 0 faster than ln|log(pi, x)| grows, so the power tends to 1. Master leaves it unevaluated after 4 s, and 2.6.0 does not finish in 30 s.
• sin(e^x (x + 1/2)) at -oo is 0. Master and 2.6.0 leave it unevaluated.

log(2 pi, log(arctan(x), tanh(x))) at 0 moved from a timeout to a decline in 3–4 s. (x^2/sinh(x))^x at 0 from the left is still 1, now in 5 s, where master took 9.5 s.

Each changed answer is in BREAKING-CHANGES.md, measured on 2.6.0. The full suite (19,118), the wrapper suites, AOT and the ten harnesses pass.

Found by limitcheck, in the A/B of #2385. No issue was filed.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.80%. Comparing base (7452b21) to head (7958a64).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2387   +/-   ##
=======================================
  Coverage   86.80%   86.80%           
=======================================
  Files         312      312           
  Lines       69190    69204   +14     
  Branches    20177    20179    +2     
=======================================
+ Hits        60060    60073   +13     
- Misses       4916     4917    +1     
  Partials     4214     4214           

Flag	Coverage Δ
cpp	37.77% <ø> (ø)
csharp	87.34% <100.00%> (+<0.01%)	⬆️
fsharp	32.97% <ø> (ø)
interactive	40.72% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...nctions/Continuous/Limits/Solvers/Limit.Classes.cs	75.76% <100.00%> (+0.82%)	⬆️

... and 1 file with indirect coverage changes

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