[Octave-bug-tracker] [bug #33601] Sparse bool matrices lose logical class with assignment of 1

[Rik]

URL:
  <http://savannah.gnu.org/bugs/?33601>

                 Summary: Sparse bool matrices lose logical class with
assignment of 1
                 Project: GNU Octave
            Submitted by: rik5
            Submitted on: Sun 19 Jun 2011 06:40:05 PM PDT
                Category: Libraries
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: None
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: GNU/Linux

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Details:

Sparse matrices support an underlying type of class double or class logical. 
The double class normally takes 8 bytes to store while the logical class only
takes 1 byte so it is advantageous to use sparse logical matrices where
possible.

Unfortunately, assignment of 0 or 1 will promote a sparse logical matrix to a
sparse double matrix even though it is unnecessary and even though the
equivalent operation using full matrices would not cause such a promotion.

Some example code:


s = sparse(false(10,10));
typeinfo(s)
ans = sparse bool matrix
s(1) = 1;
typeinfo(s)
ans = sparse matrix

The same operation on a full matrix
f = false (10,10);
typeinfo(f)
ans = bool matrix
f(1) = 1;
typeinfo(f)
ans = bool matrix







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