[Octave-bug-tracker] [bug #40105] Logical diagonal matrices are not supported

[Rik]

Update of bug #40105 (project octave):

                Severity:              3 - Normal => 2 - Minor              
                  Status:                    None => Confirmed              
                 Summary: Multiplying a logical sparse matrix by a logical
diagonal matrix gives a full matrix => Logical diagonal matrices are not
supported

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Follow-up Comment #1:

I think the problem is actually that diag doesn't support logical matrices. 
If I break the problem up I can see that the multiplication is between a
SPARSE matrix and a FULL matrix and the rules are that the SPARSE matrix is
coerced into a full matrix.


x = logical (speye (3))
x =

Compressed Column Sparse (rows = 3, cols = 3, nnz = 3 [33%])

  (1, 1) ->  1
  (2, 2) ->  1
  (3, 3) ->  1

typeinfo (x)
ans = sparse bool matrix

y = diag (logical ([1 1 1]))
y =

   1   0   0
   0   1   0
   0   0   1
typeinfo  (y)
ans = bool matrix
z = x * y
z =

   1   0   0
   0   1   0
   0   0   1
typeinfo (z)
ans = matrix


On the other hand, If I use double values which diag() does support in the
special diagonal matrix class then I get the right result.


x = speye (3);
typeinfo (x)
ans = sparse matrix
y = diag ([1 1 1])
typeinfo (y)

Diagonal Matrix

   1   0   0
   0   1   0
   0   0   1

z = x * y;
typeinfo (z)
ans = sparse matrix


I'm going to re-title the report to indicate that logical diagonal matrices
are not supported.

Simple test code for this is

typeinfo (diag ([true true true]))


which should return "logical diagonal matrix".



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