URL:
<http://savannah.gnu.org/bugs/?52127>
Summary: Difference between 32- vs. 64-bit versions of
gsl_eigen_nonsymm
Project: GNU Scientific Library
Submitted by: sudleyplace
Submitted on: Wed 27 Sep 2017 09:02:40 PM UTC
Category: Accuracy problem
Severity: 3 - Normal
Operating System: Windows 10 Pro (64-bit)
Status: None
Assigned to: None
Open/Closed: Open
Release: 2.4
Discussion Lock: Any
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Details:
I have encountered a difference in the result of gsl_eigen_nonsymm as a 32-
vs. 64-bit executable. The program is attached. What am I doing wrong?
GSL Version: 2.4
Hardware: AMD FX-8350 CPU, AUSTek Sabertooth 990FX R2.0
OS: Windows 10 Pro (64-bit)
Description:
For the 4x4 integer-valued double-precision matrix in the source file, the
32-bit executable displays results different from the 64-bit executable. I
think that the 64-bit results are correct, but they are both very close.
In particular, the results differ in the both real and imaginary parts of the
resulting Eigenvalues. For example, the 32-bit version returns the real parts
of the four Eigenvalues as
0.9999999999999996
0.9999999999999996
1.0000000000000009
1.0000000000000009
whereas the 64-bit version returns the real parts as all exactly 1. The
differences between the 32- and 64-bit results for both real and imaginary
parts are all in the low-order three bits of the hexadecimal form of the
double-precision result.
See the comments in the attached source file for the hexadecimal displays of
the real and imaginary parts.
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File Attachments:
-------------------------------------------------------
Date: Wed 27 Sep 2017 09:02:40 PM UTC Name: nonsymm.c Size: 6KiB By:
sudleyplace
<http://savannah.gnu.org/bugs/download.php?file_id=41904>
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