[bug #68091] Inefficient Integer Data Loading from MAT-Files

foreverallama <[email protected]> Wed, 25 Feb 2026 11:36:51 -0500 (EST)

Newsgroups	gmane.comp.gnu.octave.bugs
Message-ID	<[email protected]>

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URL:
  <https://savannah.gnu.org/bugs/?68091>

                 Summary: Inefficient Integer Data Loading from MAT-Files
                   Group: GNU Octave
               Submitter: foreverallama
               Submitted: Wed 25 Feb 2026 04:36:47 PM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Performance
                  Status: None
             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:


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Date: Wed 25 Feb 2026 04:36:47 PM UTC By: foreverallama <foreverallama>
Loading integer arrays from MAT-files performs an unnecessary element-wise
copy from a temporary buffer into the destination array after reading from the
stream.

OCTAVE_LOCAL_BUFFER (TYPE, ptr, len);
std::streamsize n_bytes = size * static_cast<std::streamsize> (len);

stream.read (reinterpret_cast<char *> (ptr), n_bytes);

if (swap)
  swap_bytes<size> (ptr, len);

// Unnecessary element-wise copy
for (octave_idx_type i = 0; i < len; i++)
  data[i] = ptr[I];


This introduces significant overhead for large integer variables (including
subsystem data) and can be avoided by reading directly into the target memory
or using a bulk copy.







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