bugGNU Scientific Library - Bugs: bug #61094, gsl_linalg_LU_decomp fails to...

 
 

You are not allowed to post comments on this tracker with your current authentication level.

bug #61094: gsl_linalg_LU_decomp fails to compute LU decomposition for some singular matrix

Submitter:  Anne Cheylus <anne_cheylus>
Submitted:  Tue 31 Aug 2021 01:11:11 PM UTC
   
 
Category:  Accuracy problem Severity:  3 - Normal
Operating System:  Linux Ubuntu, Mac Os X Status:  Fixed
Assigned to:  None Open/Closed:  Closed
Release:  2.6 and 2.7

Wed 01 Sep 2021 02:34:46 AM UTC, comment #1: 

Thank you for the report. This issue is fixed in commit ed23edf3f88bf6b3d7d254521b19056bee6ce1ea

Patrick Alken <psa>
Group administrator
Tue 31 Aug 2021 01:11:11 PM UTC, original submission:  

Dear GSL devloppers,

the gsl_linalg_LU_decomp gives NaN values for singular matrices with a column filled with zeros.

I have attached an example with a singular 3x3 matrix



  double a_data[] = { 0.0, 0.0, 1.0,
                      0.0, 1.0, 1.0,
                      0.0, 1.0, 2.0 };
  gsl_matrix_view m
    = gsl_matrix_view_array (a_data, 3, 3);


that finds a correct LU decomposition with GSL 2.5 but gives NaN with 2.6 and 2.7


GSL version 2.5
lu[1,:] = 0 0 1
lu[2,:] = 0 1 1
lu[3,:] = 0 1 1
p = 0 1 2



GSL version 2.6
lu[1,:] = 0 0 1
lu[2,:] = nan nan nan
lu[3,:] = nan nan nan
p = 0 1 2



Thank you very much for your attention,

Anne Cheylus




Anne Cheylus <anne_cheylus>

 

(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

Attached Files
file #51845:  output_2.5.txt added by anne_cheylus (92B - text/plain)
file #51846:  output_2.7.txt added by anne_cheylus (128B - text/plain)
file #51843:  minitestlu.c added by anne_cheylus (1KiB - application/octet-stream)
file #51844:  output_2.6.txt added by anne_cheylus (116B - text/plain)

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -email is unavailable- added by psa (Posted a comment)
  • -email is unavailable- added by anne_cheylus (Submitted the item)
  •  

    Follow 6 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2021-09-01 psa StatusNone Fixed
        Open/ClosedOpen Closed
    2021-08-31 anne_cheylus Attached File- Added output_2.6.txt, #51844
        Attached File- Added output_2.5.txt, #51845
        Attached File- Added output_2.7.txt, #51846
    2021-08-31 anne_cheylus Attached File- Added minitestlu.c, #51843

    Back to the top

    Powered by Savane 3.13-4b48.
    Corresponding source code