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2 f/\y Improved

initial writing: 2000-10-16 last updated: 2000-10-17

2 f/\y and 2 f~/\y for atomic (scalar) f and vector y are now implemented by special code. 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) .

   ts=: 6!:2 , 7!:2@]          time and space

   x=: ?. 1e5$1e9              integer
   y=: o. x                    floating point
   b=: ?. 1e5$2                boolean

Expression	J 4.06		J 4.05
2 - /\ x	0.0101418	527680	0.531219	2.09965e6	52.4  4.0
2 -~/\ x	0.0113101	527808	1.31717	2.09997e6	116.5  4.0
2 - /\ y	0.0171701	1.05197e6	0.541559	3.14822e6	31.5  3.0
2 -~/\ y	0.0160286	1.0521e6	1.32591	3.14854e6	82.7  3.0
2 - /\ b	0.00716321	657856	0.523366	1.70643e6	73.1  2.6
2 -~/\ b	0.0072378	657984	1.37632	1.70675e6	190.2  2.6
2 = /\ x	0.00491963	134464	1.31017	1.70662e6	266.3 12.7
2 = /\ y	0.031111	134464	1.39055	2.23091e6	44.7 16.6
2 = /\ b	0.00332641	264640	0.496923	1.31322e6	149.4  5.0
(}:x) - }.x	0.0310104	1.57395e6	0.0287735	1.57408e6
(}:y) - }.y	0.0524774	3.14694e6	0.0567701	3.14682e6
(}:x) = }.x	0.0288322	1.18086e6	0.0262643	1.18074e6
(}:y) = }.y	0.0636392	2.22944e6	0.0641831	2.22931e6
(}:b) = }.b	0.00508138	394432	0.00617677	394432

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