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From "Phil Steitz (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MATH-569) Add more operators to FieldElement<T>
Date Mon, 09 May 2011 18:36:03 GMT

    [ https://issues.apache.org/jira/browse/MATH-569?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13030849#comment-13030849
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Phil Steitz commented on MATH-569:
----------------------------------

negate() is OK, could be added wlog.

Regarding the others, note that a) real fields are not going to be closed under sqrt() (so
Dfp, for example, can't support this) and b) pow(.,.) requires some significant extra-algebraic
structure to be meaningful.  If you want all of this structure, then what you are really looking
for is an algebraically closed field with exp - i.e. Complex.  So the natural thing to do
is to extract a ComplexFieldElement interface, assuming this is really needed.  What exactly
are the use cases served by this?  To make it easier to implement decomposition algorithms
for both real and complex fields?  They can't rely on sqrt() if applied to real fields.

> Add more operators to FieldElement<T>
> -------------------------------------
>
>                 Key: MATH-569
>                 URL: https://issues.apache.org/jira/browse/MATH-569
>             Project: Commons Math
>          Issue Type: Improvement
>    Affects Versions: 3.0
>            Reporter: Arne Plöse
>            Priority: Minor
>
> it would be nice to have some additional operators in FieldElement i.e.
>     T negate();
>     T pow(T x);
>     T sqrt();
> maybe the double variant i.e.
>     T pow(double x);
> as well.
> This would be affect FieldVector | Matrix, BigReal, ... as well.

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