[Octave-bug-tracker] [bug #39879] expm returns inaccurate results

[anonymous]

URL:
  <http://savannah.gnu.org/bugs/?39879>

                 Summary: expm returns inaccurate results
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Tue 27 Aug 2013 01:57:48 PM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Inaccurate Result
                  Status: None
             Assigned to: None
         Originator Name: vathomas
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.6.4
        Operating System: GNU/Linux

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Details:

Hi,

I have ecountered some problem using expm function. The results I obtain have
low accuracy.

To reproduce the the problem, I have attached two files:
-expm_data is a data file containing the matrices
  tmpa     : test matrix
  expm_tmpa: result of expm(tmpa) in my PC
  expa     : expected result (checked both with matlab and an external fortran
library)
-expm_test.m is a small script file loading the data and calculating the norm
between the expected and the actual result.

In my case the norm has value 0.0953.

best regards



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File Attachments:


-------------------------------------------------------
Date: Tue 27 Aug 2013 01:57:48 PM UTC  Name: expm_data  Size: 3kB   By: None

<http://savannah.gnu.org/bugs/download.php?file_id=28941>
-------------------------------------------------------
Date: Tue 27 Aug 2013 01:57:48 PM UTC  Name: expm_test.m  Size: 282B   By:
None

<http://savannah.gnu.org/bugs/download.php?file_id=28942>

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