[Bug-gsl] [bug #45797] Possible problem with LAPACK Fortran routine ZGESVD

[Andrew Mackay]

URL:
  <http://savannah.gnu.org/bugs/?45797>

                 Summary: Possible problem with LAPACK Fortran routine ZGESVD
                 Project: GNU Scientific Library
            Submitted by: andrewm
            Submitted on: Wed 19 Aug 2015 11:39:09 AM GMT
                Category: Accuracy problem
                Severity: 3 - Normal
        Operating System: Ubuntu Linux
                  Status: None
             Assigned to: None
             Open/Closed: Open
                 Release: 2.6.32-40
         Discussion Lock: Any

    _______________________________________________________

Details:

Error in some singular vectors that appear in the standard library release for
this version of Ubuntu using Fortran routine ZGESVD. Was not present in
standard release for 2.6.31-16.
Test routine supplied for a 4x4 complex matrix and two log files. The first
log file when compiled under Linux version 2.6.31-16 (correct), the second
when compiled under Linux version 2.6.32-40 (incorrect).

The test routine is compiled by "make" with executable "svdtest"
This generates the singular values and vectors and reconstitutes the original
complex matrix. The error appears in the imaginary part of one of the left
singular vectors. Check the differences in the log files.



    _______________________________________________________

File Attachments:


-------------------------------------------------------
Date: Wed 19 Aug 2015 11:39:09 AM GMT  Name: svdcheck.zip  Size: 9kB   By:
andrewm
zipped directory containing Fortran test program and log files
<http://savannah.gnu.org/bugs/download.php?file_id=34678>

    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?45797>

_______________________________________________
  Message sent via/by Savannah
  http://savannah.gnu.org/