arrays are hashed - even if quickly, while byte chunks are constant time.
So replace both uses of the array np with a byte chunk.
i.e.
if byte i of np = "n" then next repeat
...
put "n" into byte j of np
Takes about 40% off the time.
-- Alex.
On 06/08/2018 03:36, Richard Gaskin via use-livecode wrote:
Mark Waddingham wrote:
> Richard wrote:
>>
>> Thinking about performance, I wonder if there's anything from some of
>> the changes that have boosted PHP 7's performance so far above its
>> earlier versions which may be relevant for LC:
>>
https://www.reddit.com/r/PHP/comments/3q2brz/how_is_php_7_twice_as_fast/
>
> I'd actually be really interested in a direct speed comparison between
> exactly equivalent operations in PHP7 and LC.
Geoff Canyon and I corresponded on this back in March. I don't think
he'll mind me sharing some of the relevant parts of his test:
------------------- from GC ----------------------------------------
on mouseUp
put the long seconds into T
repeat with c = 1 to 10
get get_primes(10000000)
end repeat
put "Found" && the number of lines in it && "primes in" && the long
seconds - T && "seconds"
end mouseUp
function get_primes n
if n < 2 then return empty
if n = 2 then return 2
put trunc(sqrt(n)) - 1 into mroot
repeat with i = 3 to mroot step 2
if np[i] > 0 then next repeat
add 1 to p[i]
repeat with j = i^2 to n step i
add 1 to np[j]
end repeat
end repeat
put 2 & cr & the keys of p into R
sort lines of R numeric
repeat with i = mroot + (mroot + 1) mod 2 to n - 1 step 2
if np[i] is empty then put cr & i after R
end repeat
return R
end get_primes
And that takes about fifteen minutes to run on my 2013 MacBook Pro,
where the slowest performer he's working with takes less than 30
seconds, and PHP 7 runs in under 7 seconds. Any ideas where I'm
deviating in my implementation compared to his? Here's the latest
version of his test that I found:
https://blog.famzah.net/2016/09/10/cpp-vs-python-vs-php-vs-java-vs-others-performance-benchmark-2016-q3/
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