Re: Machine epsilon, Octave and Matlab

[Geraint Bevan]

On Thu, 30 Aug 2001, John W. Eaton wrote:

> Can the original poster please run the following code on their SGI
> system?
>
>   format hex
>   on = 1
>   e2 = eps/2
>   yn = 1-e2
>   yp = 1+e2
>   t1 = 1/yn
>   t2 = 1/yp
>   df = t1-t2
>
> Here is the result I see on the Intel and AMD systems I have access
> to:
>
>   on = 3ff0000000000000
>   e2 = 3ca0000000000000
>   yn = 3fefffffffffffff
>   yp = 3ff0000000000000
>   t1 = 3ff0000000000000
>   t2 = 3ff0000000000000
>   df = 0000000000000000
>
> On the Alpha systems that I have access to (running Debian), I see
> the following results:
>
>   on = 3ff0000000000000
>   e2 = 3ca0000000000000
>   yn = 3fefffffffffffff
>   yp = 3ff0000000000000
>   t1 = 3ff0000000000001
>   t2 = 3ff0000000000000
>   df = 3cb0000000000000
>
> I expect the results on the mips-sgi system to be the same as for
> the Alpha system.
>
> Thanks,
>
> jwe
>


The original poster was actually Craig Stoudt enquiring about the
difference between Matlab and Octave under Win2000. However, you are quite
right about the result being the same on the SGI as on the Alpha:

GNU Octave, version 2.1.33 (mips-sgi-irix6.5).
Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001 John W. Eaton.
This is free software with ABSOLUTELY NO WARRANTY.
For details, type `warranty'.

*** This is a development version of Octave.  Development releases
*** are provided for people who want to help test, debug, and improve
*** Octave.
***
*** If you want a stable, well-tested version of Octave, you should be
*** using one of the stable releases (when this development release
*** was made, the latest stable version was 2.0.16).

on = 3ff0000000000000
e2 = 3ca0000000000000
yn = 3fefffffffffffff
yp = 3ff0000000000000
t1 = 3ff0000000000001
t2 = 3ff0000000000000
df = 3cb0000000000000

-- 
Geraint.




-------------------------------------------------------------
Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:  http://www.octave.org
How to fund new projects:  http://www.octave.org/funding.html
Subscription information:  http://www.octave.org/archive.html
-------------------------------------------------------------