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https://issues.apache.org/jira/browse/MATH-745?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13206867#comment-13206867
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Thomas Neidhart commented on MATH-745:
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I was curious to see if a recursion is really faster than a loop. The test
results can be seen here:
fft (calls per timed block: 1000, timed blocks: 100, time unit: ms)
name time/call std error total time ratio difference
Loop 6.97587976e-02 1.15353985e-02 6.9759e+03 1.0000e+00 0.00000000e+00
Recursive 7.11088946e-02 5.04734785e-03 7.1109e+03 1.0194e+00 1.35009693e+02
The function being transformed is sin(x).
> up to 5x Performance Improvement on FasFourierTransformer.java by using a
> recursive iterative sumation Approach
> ---------------------------------------------------------------------------------------------------------------
>
> Key: MATH-745
> URL: https://issues.apache.org/jira/browse/MATH-745
> Project: Commons Math
> Issue Type: Improvement
> Affects Versions: 3.0
> Reporter: Leandro Ariel Pezzente
> Labels: FFT, Fast, Fourier, Transform
> Attachments: FastFourierTransformer.patch.txt
>
>
> By swithinch form a loop iterative approach to a recursive iterative approach
> on fastFourierTransformer.java a Perfomance Improvement of up to 5x is gained.
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