[Maxima-bugs] [ maxima-Bugs-1751951 ] diag_matrix() with block matrices gets off-diag boxes wrong

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Bugs item #1751951, was opened at 2007-07-11 09:51
Message generated for change (Comment added) made by willisbl
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Category: None
Group: None
>Status: Pending
>Resolution: Fixed
Priority: 4
Private: No
Submitted By: Miguel Aguado (maguado)
Assigned to: Barton Willis (willisbl)
Summary: diag_matrix() with block matrices gets off-diag boxes wrong

Initial Comment:

Hello,

I couldn't find this bug among the reports, sorry if I didn't search hard enough.

The problem is related to "linearalgebra," concretely to function diag_matrix, which is said in the documentation to create appropriate off-diagonal zero blocks when its arguments are matrices.  This is not so, as in the following example:

(%i2) b1 : matrix( [ 1 ] );
(%o2)                                [ 1 ]
(%i3) b2 : matrix( [ 0, 1 ], [ 7, 9 ] );
                                   [ 0  1 ]
(%o3)                              [      ]
                                   [ 7  9 ]
(%i4) dma : diag_matrix( b1, b2 );
                                            [ 0  1 ]
(%o4)                    diag_matrix([ 1 ], [      ])
                                            [ 7  9 ]
(%i5) load("linearalgebra");
(%o5)   /usr/share/maxima/5.10.0/share/linearalgebra/linearalgebra.mac
(%i6) dma : diag_matrix( b1, b2 );
                            [  [ 1 ]     [ 0 ]   ]
                            [                    ]
(%o6)                       [ [ 0  0 ]  [ 0  1 ] ]
                            [ [      ]  [      ] ]
                            [ [ 0  0 ]  [ 7  9 ] ]

Obviously, mat_unblocker fails to handle this output.

Thanks in advance,
                           Miguel

-------------------------------------------------------------

\;

Maxima version: 5.10.0

Maxima build date: 14:57 10/18/2006

host type: i686-pc-linux-gnu

lisp-implementation-type: GNU Common Lisp (GCL)

lisp-implementation-version: GCL 2.6.7

\;

-------------------------------------------------------------



----------------------------------------------------------------------

>Comment By: Barton Willis (willisbl)
Date: 2007-07-19 11:29

Message:
Logged In: YES 
user_id=895922
Originator: NO

Fixed by linearalgebra.mac CVS revison 1.6.

(%i12) b1 : matrix( [ 1 ] );
(%o12) matrix([1])
(%i13) b2 : matrix( [ 0, 1 ], [ 7, 9 ] );
(%o13) matrix([0,1],[7,9])
(%i14) dma : diag_matrix( b1, b2 );
(%o14)
matrix([matrix([1]),matrix([0,0])],[matrix([0],[0]),matrix([0,1],[7,9])])
(%i15) mat_unblocker(%);
(%o15) matrix([1,0,0],[0,0,1],[0,7,9])


----------------------------------------------------------------------

Comment By: Barton Willis (willisbl)
Date: 2007-07-14 14:58

Message:
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user_id=895922
Originator: NO

Oh, I think that you are suggesting that size of the zero matrices in
the off-diagonal entries be adjusted so that mat_unblocker will work.
OK. I'll try to do that. 

Thanks for the bug report.


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