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Re: Transpose matrix does not work when MatrixForm is used, why?

• To: mathgroup at smc.vnet.net
• Subject: [mg45264] Re: Transpose matrix does not work when MatrixForm is used, why?
• From: nma124 at hotmail.com (steve_H)
• Date: Wed, 24 Dec 2003 17:42:18 -0500 (EST)
• References: <bruqrt$t0p$1@smc.vnet.net> <bs1b8r$9m0$1@smc.vnet.net> <200312210842.DAA18953@smc.vnet.net> <B8E20599-352B-11D8-8801-00039311C1CC@mimuw.edu.pl> <bsbmsb$lr1$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Dr Bob <drbob at bigfoot.com> wrote in message news:<bsbmsb$lr1$1 at smc.vnet.net>...

> That may be easier... if we are willing to constantly pay attention to 
> whether the target of Transpose is "wrapped" in MatrixForm or not. 
> (Transpose/@m if it's wrapped, Transpose@m if not.)
> 
> But if we want Help's claim that evaluation is not affected to be true (it 
> currently is NOT), then we have to redefine Transpose, Inverse, etc. as in 
> my example.
> 
> Only then would MatrixForm act properly as a wrapper, as intended.
> 
> Bobby
>

 
> On Tue, 23 Dec 2003 18:38:10 +0900, Andrzej Kozlowski <akoz at mimuw.edu.pl> 
> wrote:
> 
> > This of course works, but presumably he would want do this for other 
> > functions, (e.g. Inverse etc), not just transpose. So it seems to me it 
> > is easier simply to use Map:
> >
> > m = { {1, 2, 3}, {4, 5, 6} } // MatrixForm
> > Transpose/@m
> >
> > etc.
> >
> > Andrzej Kozlowski
> >


Correct Dr Bob,

But why do we have to resort to all these tricks? Why can't Mathematica just
accept a MatrixForm (or any other representation form) of the object
in its functions (Transpose in this example) just as well as the
list representation?

Each Mathematica function, where needed, could start by checking if this
'Wrapper' as you call it exists, and converts it to a list 
representation (remove the wrapper), and do its thing on the list, 
and at the end put the 'wrapper' around the result as needed and 
return the result to the user?

This way one does not have to worry which form of an object one uses,
the representation form or the list form.

i.e. representation form will be transparent to all Mathematica functions.

• Follow-Ups:
  • Re: Re: Transpose matrix does not work when MatrixForm is used, why?
    • From: Andrzej Kozlowski <akoz@mimuw.edu.pl>

• References:
  • Re: Transpose matrix does not work when MatrixForm is used, why?
    • From: drbob@bigfoot.com (Bobby R. Treat)