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Thomas Neidhart edited comment on MATH-745 at 2/13/12 1:30 PM: --------------------------------------------------------------- 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 a simple sin. was (Author: tn): 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. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira