[bug #68267] save -v4 has many inconsistencies with Matlab

Rik <[email protected]> Thu, 23 Apr 2026 04:49:43 -0400 (EDT)
Newsgroups	gmane.comp.gnu.octave.bugs
Message-ID	<[email protected]>
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URL:
  <https://savannah.gnu.org/bugs/?68267>

                 Summary: save -v4 has many inconsistencies with Matlab
                   Group: GNU Octave
               Submitter: rik5
               Submitted: Thu 23 Apr 2026 10:49:37 AM CEST
                Category: Octave Function
                Severity: 2 - Minor
                Priority: 5 - Normal
              Item Group: Matlab Compatibility
                  Status: Confirmed
             Assigned to: None
         Originator Name:
        Originator Email:
             Open/Closed: Open
         Discussion Lock: Unlocked
                 Release: dev
        Operating System: Any
           Fixed Release: None
         Planned Release: None


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Follow-up Comments:


-------------------------------------------------------
Date: Thu 23 Apr 2026 10:49:37 AM CEST By: Rik <rik5>
See this Discourse thread
https://octave.discourse.group/t/help-with-matlab-compatability-of-save-v4/7502/5

Incompatibilities noted:

1) Octave allows saving variables > 2GB


x = ones ((2^31+8) / 8, 1);
save -v4 tst2.v4 x


Matlab emits a warning and does not save the variable.

2) Octave casts unsupported variable types into double for saving


a = double (1);
b = uint8 (2);
c = char ('c');
save -v4 tst3.v4 a b c


Matlab emits a warning and does not save the *uint8* variable.  The only
supported data types are *double*, *char*, *sparse double*.

3) Octave creates corrupted data files when unsupported data type is used.


a = {1};
b = double (2);
save -v4 tst4.v4 a b
warning: save: wrong type argument 'cell'
load tst4.v4
error: load: can't read binary file


Matlab emits a warning about the wrong data type, but still saves the other
variables.










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