Re: MatrixForm
- To: mathgroup at smc.vnet.net
- Subject: [mg62574] Re: [mg62567] MatrixForm
- From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
- Date: Tue, 29 Nov 2005 04:44:04 -0500 (EST)
- References: <200511280557.AAA18494@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
On 28 Nov 2005, at 14:57, David Park wrote:
> Sometimes MatrixForm seems annoying because it is not transparent
> to other operations as some of the other Forms are. Actually, I
> think its design is very good because it allows one to write matrix
> equations with the Dot product in a nice form, and then easily
> evaluate them.
>
> A = Array[a, {2, 2}];
> B = Array[b, {2, 2}];
>
> 3 MatrixForm[A].MatrixForm[B]
> % /. MatrixForm -> Identity // MatrixForm
>
> The Dot product won't evaluate when the matrices are wrapped in
> MatrixForm and so we get the regular textbook form of a product.
> Notice also that the factor 3 was not sucked into the matrices.
> Using the rule MatrixForm -> Identity then evaluates the matrix
> multiplication.
>
> I don't know how many users are aware of this usage. I have just
> begun to appreciate it and thought I would post a note on it.
>
> David Park
> djmp at earthlink.net
> http://home.earthlink.net/~djmp/
>
This is all true but... if you replace MatrixForm with
TraditionalForm in the above you will get all the advantages
described plus a little nicer output. And, if your Default Output
Format type is set to TraditionalForm you won't need the last //
TraditionalForm.
Is there any point in keeping MatrixForm other than compatibility
with earlier versions of Mathematica?
Andrzej Kozlowski
- References:
- MatrixForm
- From: "David Park" <djmp@earthlink.net>
- MatrixForm