[Axiom-developer] [patch #2074] (new) Bug #4733 (rounding of negative numbers)

[Bill Page]

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It relates to:
                patch #2074, project Axiom Computer Algebra System

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 LATEST MODIFICATIONS of patch #2074:
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               Posted by: Bill Page <billpage1>
               Posted on: 2005-01-21 04:57 (Canada/Eastern)
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                  Status:                    None -> Applied                


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 OVERVIEW of patch #2074:
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URL:
  <http://savannah.nongnu.org/patch/?func=detailitem&item_id=2074>

                 Summary: Bug #4733 (rounding of negative numbers)
                 Project: Axiom Computer Algebra System
            Submitted by: billpage1
            Submitted on: Wed 10/15/2003 at 04:07
                Category: None
                Priority: 5 - Normal
                  Status: Applied
                 Privacy: Public
             Assigned to: billpage1
        Originator Email: 
             Open/Closed: Open

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Just adding Dylan's name, since he did most of the analysis work ...

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Follow-up Comments:


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Date: Sat 10/18/2003 at 15:35       By: Dylan Thurston <dpt>
I think this patch could be improved: the definition of shift2 could be
modified to not do multiplications (and so presumably be faster).

I also wonder how much the original authors worried about rounding behaviour
in some of these calls.

In the function 'normalize', for instance, the old semantics gave 'round
towards 0' behaviour; using the new semantics of shift, it would be easy to
give 'round towards -infinity' behaviour.  But both are wrong: the right
method for normalizing floating point numbers, to avoid accumulation of
errors, is 'round towards even'.







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File Attachments:


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Date: Wed 10/15/2003 at 04:07  Name: patch_item_2074.patch  Size: 5.37KB  
By: billpage1
patch item 2074
<http://savannah.nongnu.org/patch/download.php?item_id=2074&item_file_id=2073>

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This item URL is:
  <http://savannah.nongnu.org/patch/?func=detailitem&item_id=2074>

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