Comments on: Faster isNaN() http://jacksondunstan.com/articles/450 Mastering AS3 Mon, 14 May 2012 17:02:12 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: skyboy http://jacksondunstan.com/articles/450/comment-page-1#comment-2248 skyboy Mon, 20 Dec 2010 20:19:44 +0000 http://jacksondunstan.com/?p=450#comment-2248 Not wildly better, but a 24% improvement, certainly not insignificant. Another CPU architecture would probably have different results as well; The joys of cross-platform programming. Not wildly better, but a 24% improvement, certainly not insignificant. Another CPU architecture would probably have different results as well; The joys of cross-platform programming.

]]> By: jackson http://jacksondunstan.com/articles/450/comment-page-1#comment-2247 jackson Mon, 20 Dec 2010 19:15:47 +0000 http://jacksondunstan.com/?p=450#comment-2247 My mistake. <code>isNaN</code> is <em>not</em> in <code>Math</code>. These are good links! Assuming that <code>#ifdef UNIX</code> includes Mac OS X, it doesn't seem that the alternate version has much of an effect. I've updated the <a href="/articles/983" rel="nofollow">definitive article</a> with Windows 7 performance results, albeit on a different processor, and the results don't seem wildly better, even though the processor is somewhat faster. My mistake. isNaN is not in Math.

These are good links! Assuming that #ifdef UNIX includes Mac OS X, it doesn’t seem that the alternate version has much of an effect. I’ve updated the definitive article with Windows 7 performance results, albeit on a different processor, and the results don’t seem wildly better, even though the processor is somewhat faster.

]]> By: skyboy http://jacksondunstan.com/articles/450/comment-page-1#comment-2246 skyboy Mon, 20 Dec 2010 18:51:56 +0000 http://jacksondunstan.com/?p=450#comment-2246 It actually isn't in a different namespace, nor is it static, nor is it on the Math class: http://hg.mozilla.org/tamarin-central/file/fbecf6c8a86f/core/actionscript.lang.as#l64 The global functions, isNaN selected. http://hg.mozilla.org/tamarin-central/file/fbecf6c8a86f/core/Toplevel.cpp#l841 The C++ representation of global functions, isNaN selected. http://hg.mozilla.org/tamarin-central/file/fbecf6c8a86f/core/MathUtils.cpp#l200 The actual isNaN function, in a class used everywhere in the AVM, but not directly through AS3. http://hg.mozilla.org/tamarin-central/file/fbecf6c8a86f/core/MathClass.cpp#l41 The C++ code behind the Math class. It appears the slow down occurs simply because the test is more complex than necessary, especially on *nix machines (scroll up in MathUtils). It actually isn’t in a different namespace, nor is it static, nor is it on the Math class:

http://hg.mozilla.org/tamarin-central/file/fbecf6c8a86f/core/actionscript.lang.as#l64
The global functions, isNaN selected.

http://hg.mozilla.org/tamarin-central/file/fbecf6c8a86f/core/Toplevel.cpp#l841
The C++ representation of global functions, isNaN selected.

http://hg.mozilla.org/tamarin-central/file/fbecf6c8a86f/core/MathUtils.cpp#l200
The actual isNaN function, in a class used everywhere in the AVM, but not directly through AS3.

http://hg.mozilla.org/tamarin-central/file/fbecf6c8a86f/core/MathClass.cpp#l41
The C++ code behind the Math class.

It appears the slow down occurs simply because the test is more complex than necessary, especially on *nix machines (scroll up in MathUtils).

]]> By: jackson http://jacksondunstan.com/articles/450/comment-page-1#comment-2096 jackson Thu, 16 Dec 2010 17:25:53 +0000 http://jacksondunstan.com/?p=450#comment-2096 The reason the <code>Math</code> functions, including <code>isNaN</code> and <code>ceil</code>, are so slow is because they carry the overhead of a static function call. The actual work of testing whether or not a <code>Number</code> is NaN is trivial, so inlining it or using a non-static function greatly speeds up the process. I suspect, but haven't tested, that a static <code>myIsNaN</code> would run about as fast as <code>Math.isNaN</code>. The reason the Math functions, including isNaN and ceil, are so slow is because they carry the overhead of a static function call. The actual work of testing whether or not a Number is NaN is trivial, so inlining it or using a non-static function greatly speeds up the process. I suspect, but haven’t tested, that a static myIsNaN would run about as fast as Math.isNaN.

]]> By: Chen http://jacksondunstan.com/articles/450/comment-page-1#comment-2095 Chen Thu, 16 Dec 2010 15:08:12 +0000 http://jacksondunstan.com/?p=450#comment-2095 Aren't this tests should be compared against a static function that relies on a different namespace? (the question relates to the myCeil function as well) Aren’t this tests should be compared against a static function that relies on a different namespace? (the question relates to the myCeil function as well)

]]> By: （ZZ）Flash Player 10.1 Performance | 傲天翔 の blog http://jacksondunstan.com/articles/450/comment-page-1#comment-906 （ZZ）Flash Player 10.1 Performance | 傲天翔 の blog Sun, 10 Oct 2010 10:19:39 +0000 http://jacksondunstan.com/?p=450#comment-906 [...] Original Article [...] [...] Original Article [...]

]]> By: skyboy http://jacksondunstan.com/articles/450/comment-page-1#comment-760 skyboy Fri, 06 Aug 2010 18:14:38 +0000 http://jacksondunstan.com/?p=450#comment-760 if you have it strictly typed as a Number, then a != a is by far the fastest comparison for NaN; if it's not then, only NaN will result in true (because !(NaN == NaN)) public static function isNaN2(a:Number):Boolean { return a != a; } it'; about twice as fast as your test, and should also be faster in 10.1, but i haven't tested it if you have it strictly typed as a Number, then a != a is by far the fastest comparison for NaN; if it’s not then, only NaN will result in true (because !(NaN == NaN))

public static function isNaN2(a:Number):Boolean {
return a != a;
}

it’; about twice as fast as your test, and should also be faster in 10.1, but i haven’t tested it

]]> By: jackson http://jacksondunstan.com/articles/450/comment-page-1#comment-386 jackson Sun, 15 Nov 2009 18:55:06 +0000 http://jacksondunstan.com/?p=450#comment-386 All comparisons with NaN are false. See my article <a href="/articles/151" rel="nofollow">Details of NaN</a>. All comparisons with NaN are false. See my article Details of NaN.

]]> By: Philippe http://jacksondunstan.com/articles/450/comment-page-1#comment-385 Philippe Sun, 15 Nov 2009 10:54:04 +0000 http://jacksondunstan.com/?p=450#comment-385 And what about: if (v === NaN) And what about: if (v === NaN)

]]> By: Simon Altschuler http://jacksondunstan.com/articles/450/comment-page-1#comment-382 Simon Altschuler Wed, 11 Nov 2009 19:46:57 +0000 http://jacksondunstan.com/?p=450#comment-382 Aha, I see. Thanks! :-) Aha, I see. Thanks! :-)

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