[Octave-bug-tracker] [bug #51270] isdefinite should return 0 for zero matrices

[Rik]

Update of bug #51270 (project octave):

                  Status:                    None => Need Info              

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Follow-up Comment #1:

It's not clear to me that the answer should be zero.  One resource for
definitional issues is the Wikipedia entry on Positive Definite matrices
(https://en.wikipedia.org/wiki/Positive_definite_matrix).  According to the
text, the eigenvalues of a positive definite matrix are all positive. 
However, the eigenvalues of a matrix of zeros are all 0.  The number 0 is not
positive and therefore the matrix is not positive definite so Octave returns
-1.  The definition for positive semi-definite matrices would include 0.

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