Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!sdd.hp.com!wuarchive!uunet!lll-winken!aunro!alberta!cpsc.ucalgary.ca!ctycal!ingoldsb
From: ingoldsb@ctycal.UUCP (Terry Ingoldsby)
Newsgroups: comp.arch
Subject: Re: Compilers and efficiency
Summary: Why is distance between bits generally useful?
Message-ID: <653@ctycal.UUCP>
Date: 7 May 91 19:19:05 GMT
References: <27fa3350.6bc2@petunia.CalPoly.EDU> <9782@mentor.cc.purdue.edu> <11411@mentor.cc.purdue.edu>
Organization: The City of Calgary, Ab
Lines: 43

In article <11411@mentor.cc.purdue.edu>, hrubin@pop.stat.purdue.edu (Herman Rubin) writes:
> In article <4082@batman.moravian.EDU>, halkoD@batman.moravian.EDU (David Halko) writes:
> > In article <9782@mentor.cc.purdue.edu>, hrubin@pop.stat.purdue.edu (Herman Rubin) writes:
> > > In article <1991Apr5.172533.6717@agate.berkeley.edu>, doug@eris.berkeley.edu (Doug Merritt) writes:
> > > > In article <1991Apr4.125122.1@capd.jhuapl.edu> waltrip@capd.jhuapl.edu writes:

I had to leave the above 4 lines in, just cause it looks so awesome to see
a discussion going so many levels deep :^)
...
> Consider the following two operations, which comprise more than 25% of the 
> operations in some highly efficient, from the "picocode" standpoint, methods
> for generating non-uniform random numbers.
> 
> 1.  Examine a bit, and take some action depending on it.  Also, the next time
> this is to be done, this bit effectively no longer exists.  It is necessary
> to make provision at least somewhere for replenishing the supply of bits.
> 
> 2.  Find the distance to the next one in a bit stream.  The same considerations
> as above apply.

I have got to ask.  Why is it so generally important that the distance between
bits can be determined efficiently.  Note that I want to know, `why is it
important to ME, and to the general computing base?'.  This is the question
that hardware designers and compiler writers ask themselves.

For the hardware/software designer to incorporate the features you want, it
is not enough to know that they are important to YOU.  From
a business case, the only reason that they care if you are happy is if you
give them money.  If the desired features are generally useful, then the
probability is high that inclusion of such features will generate lots of
money.

It seems to me that the only way your crusade for bit distance will ever be
successful is to show the general utility of such functions.  Otherwise, no
matter how interesting (to you), you will not get these features.

Anyway, please tell us.  What is so interesting/useful about non-uniform
random numbers?

-- 
  Terry Ingoldsby                ingoldsb%ctycal@cpsc.ucalgary.ca
  Land Information Services                 or
  The City of Calgary       ...{alberta,ubc-cs,utai}!calgary!ctycal!ingoldsb