URL:
<https://savannah.gnu.org/bugs/?61094>
Summary: gsl_linalg_LU_decomp fails to compute LU
decomposition for some singular matrix
Project: GNU Scientific Library
Submitted by: anne_cheylus
Submitted on: mar. 31 août 2021 13:11:11 UTC
Category: Accuracy problem
Severity: 3 - Normal
Operating System: Linux Ubuntu, Mac Os X
Status: None
Assigned to: None
Open/Closed: Open
Release: 2.6 and 2.7
Discussion Lock: Any
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Details:
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
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File Attachments:
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Date: mar. 31 août 2021 13:11:12 UTC Name: output_2.5.txt Size: 92o By:
anne_cheylus
<http://savannah.gnu.org/bugs/download.php?file_id=51845>
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Date: mar. 31 août 2021 13:11:12 UTC Name: output_2.7.txt Size: 128o By:
anne_cheylus
<http://savannah.gnu.org/bugs/download.php?file_id=51846>
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Date: mar. 31 août 2021 13:11:11 UTC Name: minitestlu.c Size: 1kio By:
anne_cheylus
<http://savannah.gnu.org/bugs/download.php?file_id=51843>
-------------------------------------------------------
Date: mar. 31 août 2021 13:11:11 UTC Name: output_2.6.txt Size: 116o By:
anne_cheylus
<http://savannah.gnu.org/bugs/download.php?file_id=51844>
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