AngouriMath

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WhereBothSidesAgree​(AngouriMath.​Entity,​AngouriMath.​Entity.​Variable,​AngouriMath.​Entity)

 Method (no overloads)

Summary

The limit where the two one-sided limits agree, asked of each side through the
whole of ComputeLimit(AngouriMath.Entity,AngouriMath.Entity.Variable,AngouriMath.Entity,AngouriMath.Core.ApproachFrom,System.Boolean), or null where either side
has no answer, the two differ, or the reading is not of real-valued functions.

Remarks

A two-sided limit is the two one-sided ones agreeing, and the branch that compares
them compares two ComputeLimitDivideEtImpera results -- the bare descent --
where a caller who names a side gets that descent *and* everything behind it:
SolveAsIndeterminatePower(AngouriMath.Entity,AngouriMath.Entity.Variable,AngouriMath.Entity,AngouriMath.Core.ApproachFrom), l'Hopital's rule, and the substitution
that moves a finite destination out to infinity.
**Only under a real codomain, and that is the whole of what makes it sound.** The
promotion cannot be made over the complex plane, because there the one-sided limits
do not stay inside the reals: `lim x->0- x^x` answers 1 from the continuation, so
promoting agreement would give `lim x->0 x^x` the value 1 where `x^x` is not real
to the left of 0 at all, and `LimitTest.TestNoLimit` pins it as non-existent.
Under Real that side has no value to agree
with, so the case this could get wrong is the case that no longer arises.
Asked only where the answer would otherwise be NaN, so nothing that already answers
pays for it, and it can only ever turn a refusal into an answer.
#719,
#596

























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