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From Bernhard Gr├╝newaldt (JIRA) <j...@apache.org>
Subject [jira] Updated: (MATH-215) Fast Hadamard Transform
Date Sat, 27 Dec 2008 19:34:44 GMT

     [ https://issues.apache.org/jira/browse/MATH-215?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Bernhard Gr├╝newaldt updated MATH-215:
-------------------------------------

    Attachment: FastHadamardTransformerTest.java.diff

Implements suggestions of Luc Maisonobe - 27/Dec/08 08:51 AM
{quote}
The transform only uses two columns at a time from the matrix, wouldn't it be possible to
simply use two single dimension arrays only ?
I also think the check for n being a power of two can be done without the pow and log functions
by comparing n and Integer.highestOneBit. 
{quote}
https://issues.apache.org/jira/browse/MATH-215?focusedCommentId=12659353#action_12659353

> Fast Hadamard Transform
> -----------------------
>
>                 Key: MATH-215
>                 URL: https://issues.apache.org/jira/browse/MATH-215
>             Project: Commons Math
>          Issue Type: New Feature
>    Affects Versions: 1.0, 1.1, 1.2
>            Reporter: Daniel Kuan
>             Fix For: 2.1
>
>         Attachments: FastHadamardTransformer.java.diff, FastHadamardTransformerTest.java.diff
>
>
> To date, the mathematical transforms package of Commons Maths, org.apache.commons.math.transform,
only contains implementations for the Fourier, Sine, and Cosine transforms.
> This issue serves to propose and track the creation of an implementation for the Hadamard
transform.
> Definition of the hadamard transform:
> http://en.wikipedia.org/wiki/Hadamard_transform#Definition
> Unfortunately, Mathworld does not provide a very detailed definition.
> http://mathworld.wolfram.com/HadamardTransform.html
> An elegant algorithm for the fast hadamard transform can be found here:
> http://www.archive.chipcenter.com/dsp/DSP000517F1.html

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