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From: hook@cscsun3.larc.nasa.gov (Ed Hook)
Subject: Re: What's the best language to start with? [was: Re: Should I learn
 C or Pascal?]
Date: 1996/08/09
Message-ID: <4ufqlt$s71@reznor.larc.nasa.gov>#1/1
X-Deja-AN: 173171874
distribution: world
references: <31FBC584.4188@ivic.qc.ca>
 <01bb83ad$29c3cfa0$87ee6fce@timpent.airshields.com>
 <4u89c4$p7p@solutions.solon.com>
 <01bb83f5$923391e0$87ee6fce@timpent.airshields.com>
 <4uah1k$b2o@solutions.solon.com>
 <01bb853b$ca4c8e00$87ee6fce@timpent.airshields.com>
 <4udjki$2l8@cnn.Princeton.EDU>
organization: CSC/NASA Langley Research Center
reply-to: hook@cscsun3.larc.nasa.gov
newsgroups: comp.lang.c,comp.lang.c++,comp.unix.programmer,comp.lang.ada
Date: 1996-08-09T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <4udjki$2l8@cnn.Princeton.EDU>, tim@franck (telnet user) writes:
|> Tim Behrendsen (tim@airshields.com) wrote:
|> 
|> : This is an interesting case, because it is somewhat inefficently
|> : implemented.  If you're interested in speed, you would do...
|> 
|> : int gcd(int x, int y) {
|> :     int z;
|> :     while (y != 0)
|> :         z = y; y = x % y; x = z;
|> :     return(y);
|> : }
|> 
|> However if you are interested in correctness, you use braces for the
|> loop.  I think this case where you write assembly in C, get it wrong,
|> and ...
|>
  And ... if, in addition, you're interested in _mathematical_ correctness,
  you'll write instead:

  int gcd(int x, int y)
  {
	int z;
	while ( y != 0 ) {
		z = y;
		y = x % z;
		x = z;
	}
	return x;
   }

   On the other hand, I can greatly speed up tha given code; just replace
   it by

   int gcd(int x, int y)
   {
	return 0;
   }

   -- it does the same thing.
 
|> : Using my AIX compiler, I get a nominal improvement of about
|> : 10%, mostly because the speed of the modulo is much slower
|> : than the inefficiency of recursion.
|> 
|> only achieve a 10% speedup proves everyone else's point, and is an
|> appropriate place to end this thread.
|>

  I can't argue with that ...
 
|> ---------------------------------------------------------------------------
|> Tim Hollebeek         | Disclaimer :=> Everything above is a true statement,
|> Electron Psychologist |                for sufficiently false values of true.
|> Princeton University  | email: tim@wfn-shop.princeton.edu
|> ----------------------| http://wfn-shop.princeton.edu/~tim (NEW! IMPROVED!)

-- 
 Ed Hook                              |       Coppula eam, se non posit
 Computer Sciences Corporation        |         acceptera jocularum.
 NASA Langley Research Center         | Me? Speak for my employer?...<*snort*>
 Internet: hook@cscsun3.larc.nasa.gov |        ... Get a _clue_ !!! ...