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From "Gilles (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MATH-667) Representations of the complex numbers
Date Mon, 26 Sep 2011 11:53:26 GMT

    [ https://issues.apache.org/jira/browse/MATH-667?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13114610#comment-13114610
] 

Gilles commented on MATH-667:
-----------------------------

bq. Sounds interesting,

Actually, I thought that _you_ would be interested in implementing "BasicComplex" (along the
lines described) as this would (supposedly) provide the same behaviour as Octave. And the
the unit tests which you attached in MATH-620 would be the basis for ensuring this.

bq. but you will have to make sure that each functions [...] return the same class [...]

Currently, I see it as the returned instance will belong to the same class as "{{this}}".

> Representations of the complex numbers
> --------------------------------------
>
>                 Key: MATH-667
>                 URL: https://issues.apache.org/jira/browse/MATH-667
>             Project: Commons Math
>          Issue Type: Wish
>            Reporter: Gilles
>            Priority: Minor
>              Labels: features
>             Fix For: 3.1
>
>
> Several issues have been raised about the current behaviour of the "Complex" class, located
in package "o.a.c.m.complex" (e.g. MATH-657, MATH-620).
> The ensuing discussion revealed various, sometimes incompatible, requirements with focus
on efficiency or consistency or backwards compatibility or comparison with other math packages
(Octave) or faithfulness to standards (C99x).
> It is thus proposed to create several classes, each with a clearly defined purpose.
> The consensus seems to be that the first task is to implement a new "BasicComplex" class
where the computational formulae (for computing real and imaginary part of a complex) will
be applied directly without worrying about limiting cases (NaNs and infinities). Doing so
will automatically produce a behaviour similar to the Java {{double}} primitive. It is also
assumed that it will be the most efficient implementation for "normal" use (i.e. not involving
limiting cases).
> This task would consist in copying most of the code in the existing "Complex" class over
to "BasicComplex". And similarly with "ComplexTest". Then, in "BasicComplex", one would remove
all variables that refer to NaNs and infinities together with checks and special assignments,
and adapt the unit tests along the way.
> A new "ExtendedComplex" class would inherit from "BasicComplex". This class would aim
at representing the compactified space of the complex numbers (one point-at-infinity).
> A new "C99Complex" class would inherit from "BasicComplex". This class would aim at implementing
the C99x standard.

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