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From Gilles <gil...@harfang.homelinux.org>
Subject Re: [numbers] JTransforms and commons-math
Date Sat, 14 Jan 2017 14:33:03 GMT
Hi.

On Sat, 14 Jan 2017 11:07:12 +0100, Eric Barnhill wrote:
> On the subject of FFT and other transforms, I went to take another 
> look at
> the JTransforms code, which is AFAIK the premiere transforms package 
> for
> Java (even outperforming FFTW) and which I myself use over Commons.
>
> It is now on GitHub so it was easy to browse the source code. It is 
> in pure
> Java and even has a commons-3 dependency (on FastMath).

Do you know which methods, and why (precision and/or performance)?

> Other than that,
> from the code I looked at, it is only dependent on another package by 
> the
> same author, JLargeArrays.
>
> This must be an issue around commons from time to time. The 
> reasonable
> choice for a Java user would be JTransforms. It would be needless 
> time and
> effort to reinvent the wheel, this author has been refining the 
> package for
> 10+ years.

+1 (now)
We've known for a long time that it existed.
IIRC, originally it was not pure Java, so that would have been the main
argument for not dropping the FFT code from Commons Math.

> On the other hand we will need an FFT going forward,
As for similar issues (cf TEXT), "SigProc" can define custom interfaces
and bridge(s).

> and it is
> part of the commons mission to be self-contained.

Really?

> JTransforms is open source so it could potentially be adapted for 
> sigproc
> and numbers. For example, it doesn't take Complex arrays but only 
> double
> arrays that alternate real and imaginary, which are awkward to deal 
> with --
> that is why I wrote methods, now in ComplexUtils, to deal with it.
>
> But there's no question that overwhelmingly such an adaptation would 
> remain
> the same as the current library.

I don't understand the above sentence.

> Is there a recommended way to proceed?

To do what?


Regards,
Gilles


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