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2 f/\y Improved |
initial writing: 2005-06-08 |
2 f/\y is now implemented by special code for any verb f and any array y , removing the previous restrictions on f and y . The table below presents time and space comparisons; the bottom section of the table shows that 2 f/\x is more efficient in time and space than the equivalent (}:x) f (}.x) .
i=: 1e5 3 ?.@$ 10 integer x=: o. i floating point b=: 1e5 3 ?.@$ 2 boolean ts=: 6!:2 , 7!:2@] time and space ts 'Expression'
Expression | J 6.01 | J 5.04 | Ratio | |||||||||
2 -:/\ i | 0.00095811 | 1.325440e5 | 0.13497488 | 3.278720e6 | 140.88 | 24.74 | ||||||
2 -:/\ x | 0.00365637 | 1.325440e5 | 0.14033382 | 5.375872e6 | 38.38 | 40.56 | ||||||
2 -:/\ b | 0.00204922 | 6.568320e5 | 0.13355729 | 1.705792e6 | 65.17 | 2.60 | ||||||
2 -.@-:/\ i | 0.00095596 | 1.328640e5 | 0.17538999 | 3.279104e6 | 183.47 | 24.68 | ||||||
2 -.@-:/\ x | 0.00354134 | 1.328640e5 | 0.18362529 | 5.376256e6 | 51.85 | 40.46 | ||||||
2 -.@-:/\ b | 0.00201308 | 6.571520e5 | 0.17742993 | 1.706176e6 | 88.14 | 2.60 | ||||||
(}: -:"_1 }.) i | 0.00460509 | 4.326720e6 | 0.00476343 | 4.326720e6 | ||||||||
(}: -:"_1 }.) x | 0.01125429 | 8.521024e6 | 0.01176834 | 8.521024e6 | ||||||||
(}: -:"_1 }.) b | 0.00256332 | 1.180992e6 | 0.00249425 | 1.180992e6 |