Re: Factor MatrixForm

• To: mathgroup at smc.vnet.net
• Subject: [mg21405] Re: Factor MatrixForm
• From: Gianluca Gorni <gorni at dimi.uniud.it>
• Date: Tue, 4 Jan 2000 02:12:36 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

```I already thought about how to format a symbolic list or matrix with
a common factor collected out, and I solved it by using PolynomialGCD[]
and PrecedenceForm[].

My full code is here (the variable names are an Italian/English hybrid):

collectFactorFromLists[exprList_List] :=
Module[{fatt, sempl},
fatt = PolynomialGCD @@ Flatten[{exprList}];
If[StringMatchQ[ToString[InputForm[fatt]], "-*"],
fatt = -fatt];
sempl = If[fatt =!= 0, Simplify[Expand[exprList/fatt]]];
If[fatt === 0 || fatt === 1,
If[ByteCount[exprList] < 500,
MatrixForm[exprList], exprList],
PrecedenceForm[Simplify[fatt], 1]*
PrecedenceForm[If[ByteCount[sempl] < 500 && MatrixQ[sempl],
MatrixForm[sempl], sempl]]]];

collectFactorFromLists[expr_ /; Head[expr] =!= List] := expr;

When you want to use the output for further calculations,
you have do deformat it first by applying the rules
PrecedenceForm[a_,___]:>a and MatrixForm -> Identity.

Good luck.

Gianluca Gorni
--

+---------------------------------+
| Gianluca Gorni                  |
| Universita` di Udine            |
| Dipartimento di Matematica      |
|   e Informatica                 |
| via delle Scienze 208           |
| I-33100 Udine UD                |
| Italy                           |
+---------------------------------+
| Ph.: (39) 0432-558422           |
| Fax: (39) 0432-558499           |
| mailto:gorni at dimi.uniud.it      |
| http://www.dimi.uniud.it/~gorni |
+---------------------------------+

> a list in MatrixForm, something like this:
>
>  MatrixForm[t]
>
>  [ Cos[a]Sin[b]H - Sin[a]Sin[b]H ]
>  [ -Sin[a]k*w*H - 5*Sin[b]*k*H   ]
>  [   -2Cos[2a]H                  ]
>
> What manipulation do I perform to get it to look like
>
>    [ Cos[a]Sin[b] - Sin[a]Sin[b] ]
>  H*[ -Sin[a]k*w - 5*Sin[b]*k     ]
>    [ -2Cos[2a]                   ]
>
>
>
> --
> ----------------------------------------------------------------
>  Bob Love
>  rlove at neosoft.com
> ----------------------------------------------------------------

```

• Prev by Date: Re: FourierTransform[Sign[t], t, w, FourierParameters -> {1, -1}]
• Next by Date: Re: Eigensystem applied to a unitary matrix crashes Mathematica 4.
• Previous by thread: Re: Factor MatrixForm
• Next by thread: Re: FourierTransform[Sign[t], t, w, FourierParameters -> {1, -1}]