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/:@/: Improved

initial writing: 2004-05-19
last updated: 2004-10-26


The monads /:@/: (which computes ranking) and /:@/:"r are now implemented by special code. The following benchmarks illustrate the improvements in time and space:

ts=: 6!:2 , 7!:2@]  NB. time and space
ts '/:@/:x'
    x    J 5.04     J 5.03    Ratio
1e6 1 ?@$ 2  0.036380   4.195072e6 0.258304   1.258368e7  7.10   3.00
1e6 2 ?@$ 2  0.076345   4.195072e6 0.401466   1.258368e7  5.26   3.00
1e6 3 ?@$ 2  0.226128   8.389376e6 0.520508   1.258368e7  2.30   1.50
1e6 4 ?@$ 2  0.134970   4.195072e6 0.600956   1.258368e7  4.45   3.00
1e6 5 ?@$ 2  0.508242   8.389376e6 0.857384   1.258368e7  1.69   1.50
 
a.{~1e6 1 ?@$ #a. 0.042595   4.197120e6 0.567743   1.258368e7 13.33   3.00
a.{~1e6 2 ?@$ #a. 0.119103   4.719360e6 0.814606   1.258368e7  6.84   2.67
a.{~1e6 3 ?@$ #a. 0.698069   8.389376e6 1.099157   1.258368e7  1.57   1.50
a.{~1e6 4 ?@$ #a. 1.019201   8.389376e6 1.388238   1.258368e7  1.36   1.50
a.{~1e6 5 ?@$ #a. 1.257346   8.389376e6 1.678288   1.258368e7  1.33   1.50
 
1e6 ?@$ 1e2  0.101135   4.195584e6 0.624041   1.258368e7  6.17   3.00
1e6 ?@$ 1e4  0.116228   4.260608e6 0.714883   1.258368e7  6.15   2.95
1e6 ?@$ 1e6  0.461045   8.389376e6 1.146183   1.258368e7  2.49   1.50
1e6 ?@$ 1e8  0.806820   8.913664e6 1.194081   1.258368e7  1.48   1.41
 
1e6 ?@$ 0  1.840385   8.913664e6 2.239712   1.258368e7  1.22   1.41



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