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From: sef@kithrup.COM (Sean Eric Fagan)
Newsgroups: comp.lang.fortran,comp.lang.c
Subject: Re: Fortran vs. C for numerical work (SUMMARY)
Message-ID: <1990Nov29.040910.7400@kithrup.COM>
Date: 29 Nov 90 04:09:10 GMT
References: <17680:Nov2806:04:1090@kramden.acf.nyu.edu> <7200@lanl.gov> <2392:Nov2902:59:0590@kramden.acf.nyu.edu>
Organization: Kithrup Enterprises, Ltd.
Lines: 26

In article <2392:Nov2902:59:0590@kramden.acf.nyu.edu> brnstnd@kramden.acf.nyu.edu (Dan Bernstein) writes:
>In article <7200@lanl.gov> ttw@lanl.gov (Tony Warnock) writes:
>>     With respect to speed, almost all machines that I have used during
>>     the last 25 or so years have had faster multiplications than
>>     memory accesses.
>Hmmm. What machines do you use? In my experience (mostly mainframes and
>supers, some micros, and only recently a bit with minis) local memory
>access is up to several times as fast as integer multiplication. 

On both Cybers and Crays, multiplication can easily take fewer cycles than
accessing memory.  (No cache, remember?)  But most machines aren't like
that, I believe.

>(I
>don't like this situation; converting to floating point just to multiply
>quickly on a Cray seems rather silly.)

Uhm... you don't have to, I don't think.  A Cyber had only one type of
multiply instruction, but if the exponent were 0, it did an integer
multiplication.  I believe Cray's do the same thing.

-- 
-----------------+
Sean Eric Fagan  | "That's my weakness:  vulnerable poultry."
sef@kithrup.COM  | 
-----------------+  Any opinions expressed are mine, shared with none.