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+
on Sparse Arguments Improved
|
initial writing: 2001-08-02 last updated: 2004-10-26
|
The dyad + (and other atomic functions such as - * )
on sparse arguments are now more efficient in time and space. For example:
s=: 13 17 19
x=: ?.1600$1e6
i=: ?.(1600,#s)$s
p=: (800{.x) (<"1 ]800{.i)}1$.s
q=: (800}.x) (<"1 ]800}.i)}1$.s
ts=: 6!:2 , 7!:2@] NB. time and space
ts 'p+q'
Expression |
J 5.01 | |
J 4.06 | |
Ratio |
p + q |
0.000450895 | | 33792 | |
0.001660546 | | 153856 | |
3.68 | | 4.55 |
p - q |
0.000447822 | | 33792 | |
0.001658311 | | 153856 | |
3.70 | | 4.55 |
p * q |
0.000249473 | | 5248 | |
0.000749537 | | 52608 | |
3.00 | | 10.02 |
p % q |
0.000645613 | | 33792 | |
0.001753016 | | 153856 | |
2.72 | | 4.55 |
p = q |
0.000742552 | | 19456 | |
0.001741841 | | 127232 | |
2.35 | | 6.54 |
p ~:q |
0.000748978 | | 19456 | |
0.001632051 | | 127232 | |
2.18 | | 6.54 |
p < q |
0.000670756 | | 19456 | |
0.001730108 | | 136448 | |
2.58 | | 7.01 |
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