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[Octave-bug-tracker] [bug #65020] Issues with inv() on new intel archite

From: anonymous
Subject: [Octave-bug-tracker] [bug #65020] Issues with inv() on new intel architecture
Date: Tue, 12 Dec 2023 12:17:42 -0500 (EST)


                 Summary: Issues with inv() on new intel architecture
                   Group: GNU Octave
               Submitter: None
               Submitted: Tue 12 Dec 2023 05:17:39 PM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: Sukanta Basu
        Originator Email: sukanta.basu@gmail.com
             Open/Closed: Open
                 Release: 6.4.0
         Discussion Lock: Any
        Operating System: GNU/Linux
           Fixed Release: None
         Planned Release: None


Follow-up Comments:

Date: Tue 12 Dec 2023 05:17:39 PM UTC By: Anonymous
I am on a new workstation (Intel Xeon w9-3495X (105MB Cache, 56 cores, 112
threads, 1.9GHz to 4.8GHz Turbo 350W) running Ubuntu 22.04. Please see the
inv() and pinv() computations below. I repeat them on a different workstation
(AMD Ryzen Threadripper PRO 5995WX: 64 cores, 2.7 GHz, 256 MB cache, PCIe

GNU Octave Version: 6.4.0 (hg id: 8d7671609955)
GNU Octave License: GNU General Public License
Operating System: Linux 6.1.0-1027-oem #27-Ubuntu SMP PREEMPT_DYNAMIC Mon Nov
20 15:08:14 UTC 2023 x86_64
Package Name  | Version | Installation directory
       image *|  2.14.0 | /home/sukanta/octave/image-2.14.0
         mpi *|   3.1.0 | /home/sukanta/octave/mpi-3.1.0
octave:2> randn('seed',0);
octave:3> A = randn(100);
octave:4> B = inv(A);
octave:5> C = pinv(A);
octave:6> B(1)
ans = -172.63
octave:7> C(1)
ans = 0.4608

The same computation on AMD system: 

octave:13> randn('seed',0);
octave:14> A = randn(100);
octave:15> B = inv(A);
octave:16> C = pinv(A);
octave:17> B(1)
ans = 0.4608
octave:18> C(1)
ans = 0.4608
octave:19> version -lapack
ans = Linear Algebra PACKage Version 3.10.0
octave:20> version -blas

You will notice that the pinv() results match from both the systems.
Furthermore, inv() and pinv() from AMD match. But, inv() and pinv() on intel
are completely different. 


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