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Re^2: The golf course looks great... (Part II) ("speed")

by tye (Sage)
on May 27, 2009 at 13:07 UTC ( #766401=note: print w/replies, xml ) Need Help??


in reply to Re: The golf course looks great, my swing feels good, I like my chances (Part II)
in thread The golf course looks great, my swing feels good, I like my chances (Part II)

I chose the "19&" version of a magic formula here only because the bitwise and & operator is typically faster than the modulo % operator. BTW, an interesting (non-golf) problem is to find the most efficient magic formula: for that, I expect you'd try to use "fast" operators (such as &, ^, |, >>), while avoiding "slow" ones (such as % and /).

Your criteria probably make sense if you are writing C code. I doubt they make sense when writing in any of the languages you are actually writing in.

In particular, in Perl your fastest formula is going to be the one with the fewest operations. Dispatching a Perl opnode is going to be (I'm guessing) two or three orders of magnitude slower than even something "slow" like a division machine-language instruction.

- tye        

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[Corion]: Cosmic37: Basically, you read one file into a hash, keyed by your key, and then match the lines from the second file to that hash
[Cosmic37]: note that the two files only have datetimes which may match whereas other data per line is different format in file1 and file2 - is that really intersection?
[jedikaiti]: Hi Monks
[Corion]: Cosmic37: Well, if you want to use only parts of a line for the key, see split or whatever other mechanism to extract the key from the line
[Corion]: Hi jedikaiti!
[Cosmic37]: is there a webpage for full CB for this chat rather than side panel chat?
[Cosmic37]: thank you for advice
[Cosmic37]: peach greets jedi
[Cosmic37]: ok this one works better fullpage chat
[Cosmic37]: test

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