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From: jimb@amdcad.UUCP (Jim Budler)
Newsgroups: net.micro.mac
Subject: Re: Harmonic Series Benchmark
Message-ID: <1543@amdcad.UUCP>
Date: Fri, 7-Jun-85 13:51:47 EDT
Article-I.D.: amdcad.1543
Posted: Fri Jun  7 13:51:47 1985
Date-Received: Sat, 8-Jun-85 04:07:44 EDT
References: <1363@amd.UUCP> <6437@boring.UUCP> <1493@amdcad.UUCP> <392@gumby.UUCP>
Reply-To: jimb@amdcad.UUCP (Jim Budler)
Organization: AMD, Sunnyvale, California
Lines: 79

In article <392@gumby.UUCP> g-inners@gumby.UUCP writes:
>No, the garbage is posting a 'benchmark' that runs on only one machine.
>
>What you posted wasn't a benchmark, it was an example program for
>Mac C.  Don't advertise falsely, and you won't get flames!

What I posted was the program I used to generate times posted in
net.micro.mac, so people would know how I got the times in what I thought
was a better manner than (to quote one of the other posters) "... the
times are clocked between printf statements."

The reason I posted anything was because I spent much time trying
to find the _exact_ algorithm used by the original poster. His
verbal discription was certainly far less useful than my source code.

The _actual_ algorithm of the benchmark is only one line of
code in each precision:

	for (i = 1; i < 10000; i++) j += 1.0/i;

If that couldn't be determined by a quick scan of the code I guess
you couldn't READ C.

What do all you people do?  A C program comes over the net, you don't even
read it, but pass it through your compiler to see if it will break????

The ONLY reason that the program contained the name of the compiler
so many times was that the code started a one algorithm in double
which was then copied and pasted twice for each precision, then doubled 
again to get the output into a file as well as the screen.

A simple mechanical effort to duplicate a reasonable test of floating point
accuracy and speed has turned into a major issue. 

Your comments about a benchmark requiring portability is also rot.  The
byte, sieve of erat... benchmark is a Benchmark.  The C program to run
it is a Benchmark IMPLEMENTATION.  The Harmonic Benchmark was described
as " the sum of the first 10,000 terms of the harmonic series, with an
answer of 9.787613." I wrote an IMPLEMENTATION, and added the  doubles
answer of 9.787606.

In the intervening week before the flames started coming in the net
contained many interesting and informative comments appeared:

	1.) The series is more accurate if run in reverse.  I added
	this to my program (without posting the source), and found that
	the Mac retains accuracy in doubles.

	The new answers are 9.787604 in float, and 9.787606 in double.

	2.) We discovered that the minimum time for the series using
	SANE is 16.5 seconds.

	3.) An IBM PC AT is reported to take 1/3 the time my program 
	took.  BUT since the reporter didn't describe his method
	of timing his implementation we really don't know the exact
	speed difference.


I will admit to only TWO, count them ONE, TWO errors in that program
of any concern:
	1.) The use of // comments allowed by my compiler but not K&R.
	2.) Placing a declaration in the body of a block, again allowed
	by my compiler, but not K&R.

I do NOT want to hear again that extended is not K&R, because the use
of extended had a purpose within the meaning of the program.


Now, I'm tired of all this flaming so please direct the rest of them 
to the wastbasket.
-- 
 Jim Budler
 Advanced Micro Devices, Inc.
 (408) 749-5806
 UUCPnet: {ucbvax,decwrl,ihnp4,allegra,intelca}!amdcad!jimb
 Compuserve:	72415,1200

"... Don't sue me, I'm just the piano player!...."