Re: [Chanegset]: Re: cat does not convert sparse matrices?

[David Bateman]

David Bateman wrote:
> dbateman wrote:
> > In fact I think I see two bugs here
> >
> >
> > Francesco Potorti`-2 wrote:
> > > In Octave 3.0.1, I cannot catenate a full double matrix with a sparse
> > > logical matrix.  Is this normal or a bug?
> > >
> > > octave> a=zeros(3,3,0);
> > > octave> b1=zeros(3,3);
> > > octave> b2=sparse(1,1,true,3,3);
> > > octave> whos a b1 b2
> > >
> > > *** local user variables:
> > >
> > >   Prot Name        Size                     Bytes  Class
> > >   ==== ====        ====                     =====  =====    rwd 
> > > a           3x3x0                        0  double
> > >    rwd b1          3x3                         72  double
> > >    rwd b2          3x3                         21  logical
> > >
> > > Total is 10 elements using 93 bytes
> > >
> > > octave> size(cat(3,a,b1))
> > > ans =
> > >
> > >    3   3   1
> >
> > Trailing singleton dimensions should be dropped, So I suspect there is a
> > function call missing in the cat function that should do this.
>
> The attached patch addresses this, but
>
> > > octave> size(cat(3,a,b2))
> > > error: invalid conversion of NDArray to Matrix
> > > error: range error for insert
> > > error: evaluating argument list element number 1
> >
> > The sparse logical matrix should be promoted to a sparse matrix and the
> > concatenation allowed. Ok, I'll look at this wen I'm on a development
> > machine.
>
> It seems I missed the point you made by this one.. Sparse logical 
> matrices are promoted to sparse double matrices before concatenation 
> with another double matrix. The issue above is that a 3x3x0 is an 
> NDArray and the Sparse matrix type only supports 2D arrays and so the 
> conversion of the 3x3x0 array to a sparse matrices prior to the 
> concatenation fails. It would be interesting to know what matlab does 
> in this case, as I suspect it fails as well. If it doesn't then I 
> suppose we need to special case for this.

For this case in MatlabR2007b

>> cat(3,zeros(2,2,0),speye(2))
??? Error using ==> cat
CAT arguments dimensions are not consistent.

So it seems they don't support this either..

D.


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