[Maxima] (1.0+%i)^0.5 does not evaluate numerically
drdieterkaiser at web.de
Sat Jul 4 17:17:34 CDT 2009
Am Samstag, den 04.07.2009, 07:00 -0700 schrieb Richard Fateman:
> I think this issue is that the original programmers hesitated to make a
> single choice of a multi-valued function.
> For example, (-1)^(1/3) is simplified to -1. Arguably, wrong.
> gives 0.86602540378444*%i+0.5
> That is another possibility.
> If you plunge ahead and replace (-1)^(1/3.0) with 0.866*%i+0.5 you will
> undoubtedly get some answers more
> directly. Probably you will be closer to what Mathematica does under
> similar circumstances.
> You will presumably also get inconsistencies, as presumably does
> Note that Mathematica does NOT do (-1)^(1/3) --> -1.
Yes, the multiple-valued functions are a special problem.
But Maxima does not even numerically evaluate more simple cases with
complex arguments, e.g.
In contrast the numerically evaluation of the power function works for
real values even in the multiple-valued case using the real branch:
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