[Octave-bug-tracker] [bug #60738] logm returning incorrect result with some real non-symmetric matrices

[anonymous]

Follow-up Comment #6, bug #60738 (project octave):

Patch attached, incorporated tolerance check and 10x speedup for Hermitian
matrices.

For random matrices, I'm just using A=s*rand(n) and A=s*randn(n) or
complex(rand(n),randn(n)) of different sizes (n) and scales (s). A*=A' for
Hermitian matrices or A+=A' for symmetric not nessaraly positive definate
along with A=[21 17 6;-5 -1 -6;4 4 16]; or A=[5 4 2 1;0 1 -1 -1;-1 -1 3 0;1 1
-1 2]; for repeated eigenvalues. I'm placing the matrix at the top of the file
and checking with the max elementwise norm at the bottom
max(abs(expm(logm(A))-A)(:))

(file #51565)
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Additional Item Attachment:

File name: bug60738logm.patch             Size:3 KB
    <https://file.savannah.gnu.org/file/bug60738logm.patch?file_id=51565>



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