Path: utzoo!utgpu!attcan!uunet!rosevax!news
From: news@rosevax.Rosemount.COM (News administrator)
Newsgroups: comp.lang.c
Subject: Re: Efficient coding considered harmful?
Message-ID: <6548@rosevax.Rosemount.COM>
Date: 3 Nov 88 17:18:32 GMT
References: <3105@hubcap.UUCP> <34112@XAIT.XEROX.COM> <1700@dataio.Data-IO.COM> <8630@smoke.ARPA> <1704@dataio.Data-IO.COM> <119@twwells.uucp> <273@tijc02.UUCP>
Reply-To: merlyn@ernie.Rosemount.COM (Brian Westley)
Organization: Rosemount Inc., Burnsville, MN
Lines: 21


[profile of prime calculation]
>%time cumsecs #call ms/call name
> 82.7    4.77               _sqrt

[in code]
>    for (i = 2; i <= root(n); i++)

[note: root() calls sqrt()]

sqrt() shouldn't dominate your profile so much after you take it out
of the loop.  This isn't fortran; root() is called on every iteration.

True, some optimizations are maintenance pessimizations, but
most C compilers can't tell when function calls can be optimized out.
Thus the call for a "pure function" keyword (a function whose value is
the same for the same arguments, with no side effects).

>    Paul Schmidt

Merlyn LeRoy