Let f be a function that depends on every byte of
its argument(s). >:y and x+y are examples of
such a function, and {.y is not. The number of
cycles per byte (CPB) for f is
n %~ g * 6!:2 ' f y'
n %~ g * 6!:2 'x f y'
where n is the number of bytes in dense x, y,
or the result x f y, whichever is the greatest;
and g is the clock rate of the CPU.
For example, on an ordinary (not overclocked)
2.2 Ghz AMD 3200+ machine,
(1*m) %~ 2.2e9 * 6!:2 'm$0' [ m=: 1e7
2.34726
(4*m) %~ 2.2e9 * 6!:2 'm$2' [ m=: 1e7
2.3531
(8*m) %~ 2.2e9 * 6!:2 'm$0.2' [ m=: 1e7
2.35242
The CPB for $ is approximately 2.35.
Some others:
x=: 1e7 [EMAIL PROTECTED] 2
y=: 1e7 [EMAIL PROTECTED] 2
(#x) %~ 2.2e9 * 6!:2 'x+.y'
4.85849
(4*#x) %~ 2.2e9 * 6!:2 'x+y'
2.69899
(4*#x) %~ 2.2e9 * 6!:2 '/:x'
6.04693
(#x) %~ 2.2e9 * 6!:2 '/:~x'
3.09869
Here is something for you to think about
between eating turkeys and scoffing treats and
and stuffing stuffings and opening presents:
What is the smallest cycles per byte that you can
achieve in J? My current champion is less than 1.
(Remember, the function must depend on every byte
of its argument.)
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