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Codomain

Property

Summary

Whether functions are being read as real-valued or complex-valued. It is a
statement about the reading and not about any one expression -- an
Entity's own Codomain says what a particular node is
declared over, where this says what the library should take a function to be.

Remarks

Complex by default, which is what AngouriMath has always
done: lim x->0- ln(x) answers -oo, reading the logarithm along
its complex continuation, since the logarithm of a negative real is
ln|x| + i*pi and only its magnitude is being reported.
Under Real a limit approached through values the function
does not take in the reals has no value rather than the continued one. That is
the missing information behind a family of questions -- whether two agreeing
one-sided limits may be promoted to a two-sided one, and whether
sqrt(x^2) is x -- because each of them is answerable one way over
the reals and another over the complex plane, and the library had no way to be
told which was meant.
#719

Example

using var _ = MathS.Settings.Codomain.Set(Domain.Real);
Console.WriteLine("ln(x)".Limit("x", 0, ApproachFrom.Left));

prints the unevaluated limit, where the default prints -oo.

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Codomain