[Maxima-bugs] [ maxima-Bugs-2846665 ] Multiplication of block matrices

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Bugs item #2846665, was opened at 2009-08-28 22:20
Message generated for change (Comment added) made by willisbl
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Category: Lisp Core
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: Multiplication of block matrices

Initial Comment:
a: matrix(
 [1,2], 
 [3,4]
);
b: matrix(
 [a,a], 
 [a,a]
);
c:b.b;
gives the output for c 
matrix([matrix([2,8],[18,32]),matrix([2,8],[18,32])],[matrix([2,8],[18,32]),matrix([2,8],[18,32])])
each element in 'c' is the corresponding element of 'a' squared and then multiplied by 2.
I think the result of the multiplication of block matrices should be the same as if the matrices were unblocked.
-------------------------------------------------------------

Maxima version: 5.19.0
Maxima build date: 20:33 8/9/2009

host type: i686-pc-mingw32

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

lisp-implementation-version: GCL 2.6.8


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>Comment By: Barton Willis (willisbl)
Date: 2009-08-29 06:06

Message:
Maybe you want to set matrix_element_mul  to "."

(%i6) matrix_element_mul : "."$
(%i7) a: matrix([1,2],
[3,4]);
b: matrix([a,a],[a,a]);
c:b.b;
(%o7) matrix([1,2],[3,4])
(%o8)
matrix([matrix([1,2],[3,4]),matrix([1,2],[3,4])],[matrix([1,2],[3,4]),matrix([1,2],[3,4])])
(%o9)
matrix([matrix([2,8],[18,32]),matrix([2,8],[18,32])],[matrix([2,8],[18,32]),matrix([2,8],[18,32])])

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

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