[Rafael-SOWNet]

sin(x^2 + x - 1) from the left at 0 was left unevaluated, as on 2.6.0, and so were its two-sided limit and the tangent's.

A one-sided limit at a finite point moves the variable out to infinity, and the value read off there keeps the infinity in it: x^2 + x - 1 from the left at 0 comes back as -1 - 1/+oo + 1/+oo^2. That is -1, but the sine above it asks whether it is finite, is told no, and declines.

The argument's limit is now folded for the six trigonometric functions. They have no cut, and are continuous at every finite argument short of a pole.

Not folded for every caller, deliberately. The first version folded in SolveBySubstitution itself. That answered arctan on its cut and x! at its pole -1, which the descent had declined only because the infinity was still there. limitcheck then read arctan(ln(x))^2 at -1+ as arctan(ln(-1))^2, the value on the cut, and three tests failed.

limitcheck, DEPTH=3, seeds 14, 16, 19, 23 and 26, against master f73ac9a:

	master	this branch
compared	25 958	25 961
the limit is another value	6	6
the limit is NaN where the values settle	69	69

The three newly answered limits are cos(sinh(x) + x + 1) at -1, from the right and from both sides, and tan(x^2 + x - 1) at 0 from both sides. This also turns the two rows of #2360's test that it allowed to decline into required answers. Suite, AOT and the harnesses are green locally.

Found by limitcheck at SEED=26; no issue was filed.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.78%. Comparing base (f73ac9a) to head (b315650).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2361      +/-   ##
==========================================
- Coverage   86.78%   86.78%   -0.01%     
==========================================
  Files         312      312              
  Lines       68815    68818       +3     
  Branches    20048    20050       +2     
==========================================
+ Hits        59724    59726       +2     
- Misses       4908     4909       +1     
  Partials     4183     4183              

Flag	Coverage Δ
cpp	37.77% <ø> (ø)
csharp	87.33% <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	73.62% <100.00%> (+0.29%)	⬆️

... and 5 files with indirect coverage changes

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