Path: utzoo!attcan!uunet!crdgw1!jupiter!kassover
From: kassover@jupiter.crd.ge.com (David Kassover)
Newsgroups: comp.graphics
Subject: Re: World Cordinate Resolution
Keywords: Accuracy, floating point VS real numbers
Message-ID: <6775@crdgw1.crd.ge.com>
Date: 12 Apr 90 16:40:36 GMT
References: <20582@versatc.versatec.COM>
Sender: news@crdgw1.crd.ge.com
Organization: Aule-Tek, Inc.
Lines: 32

In article <20582@versatc.versatec.COM> ritter@versatc.versatec.COM (Jack Ritter) writes:
...
>If your're careful about over/under flow, you dont
>need all those exponent bits. What if you define
>your world space span as: -10000 to 10000, for
>example? Does this convert surplus exponent bits
>into additional accuracy bits, or does it just
>make the holes in floating-point-space bigger?

you'd want to know more about your underlying architecture...
Your mileage will vary from place to place:

binary machine,      56 bit mantissa 8 bit exponent
                     54 bit mantissa 10 bit exponent
                     63 bit mantissa 9 bit exponent
hexadecimal machine  56 bit mantissa 8 bit exponent

will all give you slightly different results.

Not to mention one architecture I know of which uses a 56 bit
integer, so the float hardware can be used for strictly integer
calculations.

Or you can write your program in Ada and design your own
arithmetic.  Watch out for performance hits if you do something
to outre wrt the actual hardware...

--
===================================================
David Kassover
kassover@ra.crd.ge.com
kassover@crd.ge.com