[Octave-bug-tracker] [bug #59486] p variable not always defined in eigs function

[JD]

URL:
  <https://savannah.gnu.org/bugs/?59486>

                 Summary: p variable not always defined in eigs function
                 Project: GNU Octave
            Submitted by: jdbancal
            Submitted on: Thu 19 Nov 2020 05:48:24 PM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Regression
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
                 Release: 6.0.92
         Discussion Lock: Any
        Operating System: GNU/Linux

    _______________________________________________________

Details:

When computing just a few eigenvalues of a matrix, Matlab supports two
syntaxes (see https://fr.mathworks.com/help/matlab/ref/eigs.html ):

A = eye(5);
eigs(A, 1)

as well as

A = eye(5);
eigs(A, [], 1)


The second format allows to disambiguate between standard and generalized
eigenvalue decompositions (this is not obvious when the first argument is a
scalar for instance). Namely, an empty second argument here makes it clear
that we are interested in the standard eigenvalue decomposition, even when the
dimension of the first argument 'A' happens to be of dimension 1x1, i.e. a
scalar.

The second syntax was supported in previous versions of Octave (4.2 for
instance), but it gives an error on the newest versions, including Octave 6:

error: 'p' undefined near line 231 column 11
error: called from
    eigs at line 231 column 7






    _______________________________________________________

Reply to this item at:

  <https://savannah.gnu.org/bugs/?59486>

_______________________________________________
  Message sent via Savannah
  https://savannah.gnu.org/