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<div class=Section1>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Daan –<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Curmudgeons? On THIS list? I’m shocked – shocked, I
say!<o:p></o:p></span></p>
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mso-list:l0 level1 lfo2'><![if !supportLists]><span style='font-size:11.0pt;
font-family:"Calibri","sans-serif";color:#1F497D'><span style='mso-list:Ignore'>-<span
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</span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Ed<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
proj-bounces@lists.maptools.org [mailto:proj-bounces@lists.maptools.org] <b>On
Behalf Of </b>strebe@aol.com<br>
<b>Sent:</b> Friday, January 18, 2008 4:28 PM<br>
<b>To:</b> proj@lists.maptools.org<br>
<b>Subject:</b> [Proj] Re: Premature optimization [was NAD problems on OSX
10.5Leopard]<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal><span style='font-family:"Arial","sans-serif"'><br>
Not to be a curmudgeon, Ed (and Norman), but that isn't what the quote means,
and that is exactly what I meant by "Often misunderstood to mean,
'Engineering for scalability is the root of all evil.'" The original
quote, in its full glory, is "We should forget about small efficiencies,
say about 97% of the time: premature optimization is the root of all
evil." It is the "small efficiencies" disclaimer that is
important.<br>
<br>
Let us say your program is required (amongst many other operations) to sort a
lot of numbers. You know from the beginning that "a lot" isn't just
some fixed 12 values; it's arbitrarily large. But, in order to avoid
"premature optimization", you throw in a simple bubble sort and
proceed with the remainder of your programming.<br>
<br>
Well. You haven't avoided premature optimization. You've written the
wrong program. It won't scale. Bubble sort's execution time increases
exponentially as the number of items to sort increase. It's inappropriate for
any but the tiniest counts of numbers. You should have used quicksort instead.
C.A.R. Hoare knew this and had it in mind — he did, after all, invent
quicksort.<br>
<br>
Yet I constantly run into colleagues who excuse their program's performance
failures running under stress as, "Oh, I wanted to get it working; now we
can optimize it." Well. Optimizing means tuning your algorithm. It doesn't
mean replacing your algorithm. If you replace it, you're writing a new program.
You have completely lost the benefit of concentrating on the algorithm instead
of the performance details.<br>
<br>
The correct interpretation is, "Choose the correct algorithm; tune it
later if you need to."<br>
<br>
Regards,<br>
-- daan Strebe</span><o:p></o:p></p>
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