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LeavesTheRealsOnTheApproach​(AngouriMath.​Entity,​AngouriMath.​Entity.​Variable,​AngouriMath.​Entity,​AngouriMath.​Core.​ApproachFrom)

 Method (no overloads)

Summary

Whether the expression takes values outside the reals on the way in. Under a real
codomain such a limit has no value, rather than the value its complex continuation
approaches.

Remarks

lim x->0- ln(x) is the plain case: the logarithm of a negative real is
ln|x| + i*pi, and answering -oo reports the magnitude of something
that is not a real number at any point of the approach.
Decided by sampling rather than symbolically, and deliberately: what is being asked
is whether the function *takes* non-real values near a point, which no property of
the tree answers. The direction of error is chosen too. A sample that cannot be
evaluated, or that comes back non-finite, is passed over rather than counted, and an
expression carrying a second variable is not judged at all -- so the answer is only
ever "yes, demonstrably" or "not shown", and a limit is withdrawn on evidence.
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