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From: bernie@metapro.DIALix.oz.au (Bernd Felsche)
Newsgroups: comp.software-eng
Subject: Re: Effect of execution-speed on reliability/testing
Message-ID: <1991Jan12.093726.4935@metapro.DIALix.oz.au>
Date: 12 Jan 91 09:37:26 GMT
References: <1990Dec19.102005.11830@engin.umich.edu> <470@eiffel.UUCP> <1047@gistdev.gist.com> <15809.278a0d04@levels.sait.edu.au> <12212@pucc.Princeton.EDU>
Organization: MetaPro Systems, Perth, Western Australia
Lines: 38

In <12212@pucc.Princeton.EDU> EGNILGES@pucc.Princeton.EDU (Ed Nilges) writes:

[.. notes about "CORRECTNESS" deleted ]
>                               ...   As to speed, you shouldn't even
>worry about it until you have a correct program, and ....

I beg to differ!  I don't believe one line of code should be 
written until the most efficient method of calculating the
correct result has been determined.

As with all engineering problems, there is always more than
one solution to a problem.  If you don't seriously consider at least
half a dozen significantly different ones, then you are doing
yourself and your client a dis-service.

Far too much code gets generated which produces the "right" numbers,
but takes forever to crunch.  Some more thought about the problem,
before the keyboard got bashed, would have revealed much more 
efficient and manageable code, giving results in a far shorter time.

I have seen code to drive graphics displays, which used trig
functions to compute pixel positions for drawing circles.  (OK,
that's given away that I'm not exactly new to this game.) There 
is nothing wrong with this, but a more efficient, sufficiently 
correct solution is obvious to anybody skilled in the art.

Often the excuse is:  The client wants it now.  But consider the
fact that what the client gets will be an inferior product.  Put
yourself in the client's position, and see how much confidence it
inspires!  (Gee, why'd I have to buy a Stardent when something mucch
like it runs quicker on my Sinclair QL?)

QUALITY is more than just getting the right numbers. More EFFICIENT
code is not always less reliable.
-- 
______________________________Bernd_Felsche______________________________
Metapro Systems, 328 Albany Highway, Victoria Park Western Australia 6100
Phone: +61 9 362 9355   Fax: +61 9 472 3337   bernie@metapro.DIALix.oz.au