Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!rex!rouge!cacs.usl.edu
From: pcb@cacs.usl.edu (Peter C. Bahrs)
Newsgroups: comp.windows.ms.programmer
Subject: Actor: bad numerical precision?
Message-ID: <20060@rouge.usl.edu>
Date: 5 Dec 90 05:22:54 GMT
Sender: anon@rouge.usl.edu
Organization: The Center for Advanced Computer Studies, USL
Lines: 28

Was: arghh!

I just wrote an inverse method for a matrix class using simple row
reduction.  
   a:=inverse(c);
   b:=a*c;

Most of the time b is  1. 0. 0.
                       0. 1. 0.
                       0. 0. 1.
for a 3x3 matrix.
But sometimes, using different values for c, b is
                       1. 3.343434343-e20 1.2323-316
                       0.  1. 0.
                       0.  0. 1.

???What gives, I am confident the algorithm is correct.  It works most
of the time.  But this is a terrible error factor here that will build
up in time.  Is Actor weak in numerical precison?

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| Peter C. Bahrs                                                         |
| The USL-NASA Project                                                   |
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