Details Ticket 823


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Serial Number 823
Subject rast problems dealing with null maps on DEC Alpha (Linux)
Area bug
Queue grass
Requestors Kim.Covil@csiro.au
Owner gclements
Status stalled
Last User Contact Fri Nov 16 18:32:02 2001 (7 yr ago)
Current Priority 70
Final Priority 70
Due No date assigned
Last Action Mon Nov 19 19:22:57 2001 (7 yr ago)
Created Fri Nov 2 06:21:18 2001 (7 yr ago)

Transaction History Ticket 823


Fri, Nov 2 2001 06:21:18    Request created by guest  
Subject: rast problems dealing with null maps on DEC Alpha (Linux)

Platform: Linux/Alpha64
Linux distro: Debian
linux cpu: Alpha
Xwindows version: XFree 4.1.0
Xwindows manager: KDE 2.x
TclTk version: tcl/tk 8.3
grass downloaded at: Baylor site
grass binary for platform: I compiled the sources myself
grass sources source: no, I got a source code package from the server, 
5.0.0pre2
c compiler name: gcc

Anything to do with floating point raster maps with null map on a DEC Alpha 
causes a 
floating point exception... FIX taken from source of Grass 4.2.1 with FP + 
NULL patches is to not use NaN to mark nulls in floating point maps but 
rather to use FLT_MAX...

I could probably make a patch available if required... but if is #if 0 
marked on code I am using here...
Fri, Nov 2 2001 08:14:36    Mail sent by glynn.clements@virgin.net  
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Delivered-To grass-bugs@mailman.intevation.de
From Glynn Clements <glynn.clements@virgin.net>
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Message-ID <15330.18276.28996.904287@cerise.nosuchdomain.co.uk>
Date Fri, 2 Nov 2001 07:12:36 +0000
To Request Tracker <grass-bugs@intevation.de>
Cc grass5@grass.itc.it
Subject Re: [GRASS5] [bug #823] (grass) rast problems dealing with null maps on DEC Alpha (Linux)
In-Reply-To <20011102052118.E44DE13A07@mailman.intevation.de>
References <20011102052118.E44DE13A07@mailman.intevation.de>
X-Mailer VM 6.94 under 21.4 (patch 4) "Artificial Intelligence (candidate #1)" XEmacs Lucid
Request Tracker wrote:

> Subject: rast problems dealing with null maps on DEC Alpha (Linux)

> Anything to do with floating point raster maps with null map on a DEC Alpha
> causes a 
> floating point exception... FIX taken from source of Grass 4.2.1 with FP +
> NULL patches is to not use NaN to mark nulls in floating point maps but 
> rather to use FLT_MAX...

That isn't a fix, but a workaround.

Do you have any idea what causes the FP exception? Or is it any
attempt to perform FP operations on NaN values?

-- 
Glynn Clements <glynn.clements@virgin.net>


Fri, Nov 2 2001 10:32:53    Mail sent by Kim.Covil@csiro.au  
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Delivered-To grass-bugs@mailman.intevation.de
Subject Re: [bug #823] (grass) rast problems dealing with null maps on DEC Alpha (Linux)
From Kim Covil <Kim.Covil@csiro.au>
To Glynn Clements via RT <grass-bugs@intevation.de>
In-Reply-To <20011102071436.7D57613A07@mailman.intevation.de>
References <20011102071436.7D57613A07@mailman.intevation.de>
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Date 02 Nov 2001 17:32:40 +0800
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True... you are right it is a work around... my guess is that it is any
attempt to perform FP operations on NaN values... it might be possible
to do a bit by bit comparison but the speed penalty for that would be
prohibitive...

I'll see if I can locate some Alpha documentation...

Cheers

Kim

On Fri, 2001-11-02 at 15:14, Glynn Clements via RT wrote:
> 
> Request Tracker wrote:
> 
> > Subject: rast problems dealing with null maps on DEC Alpha (Linux)
> 
> > Anything to do with floating point raster maps with null map on a DEC Alpha
> > causes a 
> > floating point exception... FIX taken from source of Grass 4.2.1 with FP
+ 
> > NULL patches is to not use NaN to mark nulls in floating point maps but 
> > rather to use FLT_MAX...
> 
> That isn't a fix, but a workaround.
> 
> Do you have any idea what causes the FP exception? Or is it any
> attempt to perform FP operations on NaN values?
> 
> -- 
> Glynn Clements <glynn.clements@virgin.net>
> 
> 
> --- Headers Follow ---
> 
> >From glynn.clements@virgin.net  Fri Nov  2 08:14:35 2001
> Return-Path: <glynn.clements@virgin.net>
> Delivered-To: grass-bugs@mailman.intevation.de
> Received: from omecihuatl.rz.uni-osnabrueck.de (omecihuatl.rz.Uni-Osnabrueck.DE
[131.173.17.35])
> 	by mailman.intevation.de (Postfix) with ESMTP id B400013A02
> 	for <grass-bugs@intevation.de>; Fri,  2 Nov 2001 08:14:35 +0100 (CET)
> Received: from mta1-svc.virgin.net (mta1-svc.virgin.net [62.253.164.41])
> 	by omecihuatl.rz.uni-osnabrueck.de (8.11.1/8.11.1) with ESMTP id fA27EZf13267
> 	for <grass-bugs@intevation.de>; Fri, 2 Nov 2001 08:14:35 +0100
> Received: from cerise.nosuchdomain.co.uk ([62.252.1.17])
>           by mta1-svc.virgin.net (InterMail vM.4.01.02.27 201-229-119-110)
>           with ESMTP
>           id <20011102071434.YAIR29561.mta1-svc.virgin.net@cerise.nosuchdomain.co.uk>;
>           Fri, 2 Nov 2001 07:14:34 +0000
> Received: (from glynn@localhost)
> 	by cerise.nosuchdomain.co.uk (8.11.6/8.11.6) id fA27Ca000999;
> 	Fri, 2 Nov 2001 07:12:36 GMT
> From: Glynn Clements <glynn.clements@virgin.net>
> MIME-Version: 1.0
> Content-Type: text/plain; charset=us-ascii
> Content-Transfer-Encoding: 7bit
> Message-ID: <15330.18276.28996.904287@cerise.nosuchdomain.co.uk>
> Date: Fri, 2 Nov 2001 07:12:36 +0000
> To: Request Tracker <grass-bugs@intevation.de>
> Cc: grass5@grass.itc.it
> Subject: Re: [GRASS5] [bug #823] (grass) rast problems dealing with null maps
on DEC Alpha (Linux)
> In-Reply-To: <20011102052118.E44DE13A07@mailman.intevation.de>
> References: <20011102052118.E44DE13A07@mailman.intevation.de>
> X-Mailer: VM 6.94 under 21.4 (patch 4) "Artificial Intelligence (candidate
#1)" XEmacs Lucid
> 
> -------------------------------------------- Managed by Request Tracker
-- 
===========================================================================
Kim Covil - CSIRO Exploration & Mining  E-mail:  kim.covil@csiro.au 
,-_!\
            PO Box 1130, Bentley,       Direct:  +61 8 6436 8638    /   
\
            Western Australia  6102     Fax:     +61 8 6436 8555   
*_,-._/
========================================================================
v
        Please direct all personal e-mail to kimbotha@covil.com.au


Thu, Nov 15 2001 16:17:00    Mail sent by glynn.clements@virgin.net  
Return-Path <glynn.clements@virgin.net>
Delivered-To grass-bugs@lists.intevation.de
From Glynn Clements <glynn.clements@virgin.net>
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Message-ID <15347.56259.105370.669945@cerise.nosuchdomain.co.uk>
Date Thu, 15 Nov 2001 15:14:11 +0000
To Request Tracker <grass-bugs@intevation.de>
Cc grass5@grass.itc.it
Subject Re: [GRASS5] [bug #823] (grass) rast problems dealing with null maps on DEC Alpha (Linux)
In-Reply-To <20011102052118.E44DE13A07@mailman.intevation.de>
References <20011102052118.E44DE13A07@mailman.intevation.de>
X-Mailer VM 6.94 under 21.4 (patch 4) "Artificial Intelligence (candidate #1)" XEmacs Lucid
Request Tracker wrote:

> this bug's URL: http://intevation.de/rt/webrt?serial_num=823
> -------------------------------------------------------------------------
> 
> Subject: rast problems dealing with null maps on DEC Alpha (Linux)
> 
> Platform: Linux/Alpha64
> Linux distro: Debian
> linux cpu: Alpha
> Xwindows version: XFree 4.1.0
> Xwindows manager: KDE 2.x
> TclTk version: tcl/tk 8.3
> grass downloaded at: Baylor site
> grass binary for platform: I compiled the sources myself
> grass sources source: no, I got a source code package from the server, 
> 5.0.0pre2
> c compiler name: gcc
> 
> Anything to do with floating point raster maps with null map on a DEC Alpha
> causes a 
> floating point exception... FIX taken from source of Grass 4.2.1 with FP +
> NULL patches is to not use NaN to mark nulls in floating point maps but 
> rather to use FLT_MAX...

Can you try compiling with the "-mieee" switch, e.g.

	CFLAGS=-mieee ./configure ...

The "gcc" Info file suggests that the Alpha's floating-point support
takes some shortcuts, which result in NaN and infinity not working:

`-mieee'
     The Alpha architecture implements floating-point hardware
     optimized for maximum performance.  It is mostly compliant with
     the IEEE floating point standard.  However, for full compliance,
     software assistance is required.  This option generates code fully
     IEEE compliant code _except_ that the INEXACT FLAG is not
     maintained (see below).  If this option is turned on, the CPP
     macro `_IEEE_FP' is defined during compilation.  The option is a
     shorthand for: `-D_IEEE_FP -mfp-trap-mode=su -mtrap-precision=i
     -mieee-conformant'.  The resulting code is less efficient but is
     able to correctly support denormalized numbers and exceptional
     IEEE values such as not-a-number and plus/minus infinity.  Other
     Alpha compilers call this option `-ieee_with_no_inexact'.

-- 
Glynn Clements <glynn.clements@virgin.net>


Fri, Nov 16 2001 18:32:02    Mail sent by mneteler  
Glynn committed a patch to configure addressing the problem.
Fri, Nov 16 2001 18:32:21    Priority changed to 70 by mneteler  
Mon, Nov 19 2001 19:22:21    Status changed to stalled by gclements  
Mon, Nov 19 2001 19:22:57    Taken by gclements  
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