[Maxima-bugs] [ maxima-Bugs-1910043 ] Wrong calculation with nested matrices

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Bugs item #1910043, was opened at 2008-03-08 06:12
Message generated for change (Comment added) made by willisbl
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Category: Lisp Core - Complex
Group: None
>Status: Pending
>Resolution: Invalid
Priority: 5
Private: No
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: Wrong calculation with nested matrices

Initial Comment:
If I am not mistaking, these two calculations should yield the same result, but do not in Maxima:

input: matrix([0,0,0,1],[0,0,1,0],[0,-1,0,0],[-1,0,0,0]).matrix([0,0,0,-%i],[0,0,%i,0],[0,%i,0,0],[
 -%i,0,0,0]);

output: matrix([-%i,0,0,0],[0,%i,0,0],[0,0,-%i,0],[0,0,0,%i])


input: matrix([0,matrix([0,1],[1,0])],[matrix([0,-1],[-1,0]),0]).matrix([0,matrix([0,-%i],[%i,0])],[matrix([0,%i],[-%i,0]),0]);

output: matrix([matrix([0,%i],[-%i,0]),matrix([0,0],[0,0])],[matrix([0,0],[0,0]),matrix([0,%i],[-%i,0])])

thus, there is something wrong, or am I wrong with that?

Maxima version: 5.12.0Maxima build date: 15:52 7/20/2007host type: i686-pc-linux-gnulisp-implementation-type: GNU Common Lisp (GCL)lisp-implementation-version: GCL 2.6.7

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>Comment By: Barton Willis (willisbl)
Date: 2008-03-08 08:25

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

To work with nested (or block) matrices, you'll need to set
matrix_element_mult to ".". Try this

(%i17) matrix_element_mult  : "."$
(%i18) 
matrix([0,matrix([0,1],[1,0])],[matrix([0,-1],[-1,0]),0]).matrix([0,matrix([0,-%i],[%i,0])],[matrix([0,%i],[
 -%i,0]),0])$
(%i20) mat_unblocker(%);
(%o20) matrix([-%i,0,0,0],[0,%i,0,0],[0,0,-%i,0],[0,0,0,%i])


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