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MathGroup Archive 2004

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Bug report for MathixExp applied to a matrix of more-than-machine-precision numbers.

  • To: mathgroup at smc.vnet.net
  • Subject: [mg46749] Bug report for MathixExp applied to a matrix of more-than-machine-precision numbers.
  • From: Oleksandr Pavlyk <pavlyk at phys.psu.edu>
  • Date: Fri, 5 Mar 2004 01:47:00 -0500 (EST)
  • Organization: Penn State University; Department of Physics
  • Reply-to: pavlyk at phys.psu.edu
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

I am not sure on how to report a bug in Mathematica, so
I would write to the forum, knowing that the list is
modetated :)

In[1]:=
$Version

Out[1]=
"5.0 for Microsoft Windows (June 11, 2003)"

In[2]:=
mat = {{0, 
0.6151525466966055419759862386321433310005256421644620580451761964922`49.296724682967415, 

-0.7254275036630691476762861174949573251764090399344597452533905218986`49.296724682967415}, 
 
{-0.6151525466966055419759862386321433310005256421644620580451761964922`49.296724682967415, 
0,
-1.2037607176452254987349374498805075260847239397930119102841747928461`49.296724682967415}, 

{0.7254275036630691476762861174949573251764090399344597452533905218986`49.296724682967415, 

1.2037607176452254987349374498805075260847239397930119102841747928461`49.296724682967415, 
0}};

In[3]:=
MatrixExp[mat]

generates  Divide::indet,  Divide::infy, \[Infinity]::"indet" errors
before Windows reports a crash of MathKernel, and shuts it down 
prompting to report the incident to Microsoft.

Trying to reduce the accuracy helps to get the final result

In[4]:=
MatrixExp[N[mat,5]]

Out[4]=
{{0.6297160719436076796`3.7756975065769325, 
0.0432721390753584633`2.6576010298827444,
    -0.7756190709530262614`3.833969641768763}, 
{-0.7581218549510174401`3.8696850920659425,
    0.25200848487286692`3.4668879073986285, 
-0.6014503110645328147`3.693042910203886},
   {0.1694363428295855821`3.1961977983341225, 
0.9667568181352670783`3.8868215583540806,
    0.1914994511208260971`3.1806736750156337}}

Best regards,
Sasha


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