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https://issues.apache.org/jira/browse/SPARK-8471?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Feynman Liang updated SPARK-8471:
---------------------------------
    Description: 
Discrete cosine transform (DCT) is an invertible matrix transformation commonly 
used to analyze signals (e.g. audio, images, video) in the frequency domain. In 
contrast to the FFT, the DCT maps real vectors to real vectors. The DCT is 
oftentimes used to provide an alternative feature representation (e.g. 
spectrogram representations of audio and video) useful for classification and 
frequency-domain analysis.

Ideally, an implementation of the DCT should allow both forward and inverse 
transforms. It should also work for any numeric datatype and both 1D and 2D 
data.

  was:
Discrete cosine transform (DCT) is an invertible matrix transformation commonly 
used to analyze signals (e.g. audio, images, video) in the frequency domain. In 
contrast to the FFT, the DCT maps real vectors to real vectors. The DCT is 
oftentimes used to provide an alternative feature representation (e.g. 
spectrogram representations of audio and video) useful for classification and 
frequency-domain analysis.

Ideally, an implementation of the DCT should allow both forward and inverse 
transforms. It should also work for any numeric datatype and 1,2, or 3 
dimensional data.


> Implement Discrete Cosine Transform feature transformer
> -------------------------------------------------------
>
>                 Key: SPARK-8471
>                 URL: https://issues.apache.org/jira/browse/SPARK-8471
>             Project: Spark
>          Issue Type: New Feature
>          Components: ML
>            Reporter: Feynman Liang
>            Assignee: Feynman Liang
>            Priority: Minor
>
> Discrete cosine transform (DCT) is an invertible matrix transformation 
> commonly used to analyze signals (e.g. audio, images, video) in the frequency 
> domain. In contrast to the FFT, the DCT maps real vectors to real vectors. 
> The DCT is oftentimes used to provide an alternative feature representation 
> (e.g. spectrogram representations of audio and video) useful for 
> classification and frequency-domain analysis.
> Ideally, an implementation of the DCT should allow both forward and inverse 
> transforms. It should also work for any numeric datatype and both 1D and 2D 
> data.



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