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Re: Automatic Display in MatrixForm

  • To: mathgroup at smc.vnet.net
  • Subject: [mg19503] Re: Automatic Display in MatrixForm
  • From: colin at tri.org.au (Colin Rose)
  • Date: Sat, 28 Aug 1999 15:53:22 -0400
  • Organization: Theoretical Research Institute
  • References: <7p00rp$76g@smc.vnet.net> <7p30am$aos@smc.vnet.net> <7ps4js$joc@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Dave Withoff apparently suggested:

MakeBoxes[m_?(Function[t,MatrixQ[Unevaluated[t]]&&(t=!={{}}),HoldAll]),
 StandardForm] :=
  RowBox[{"(", GridBox[Map[Function[t,MakeBoxes[t,StandardForm],HoldAll],
          Unevaluated[m],{2}]],")"}]


Two interesting cases are:

(1)    Output from Solve will now get displayed as a 'Matrix',
       which I think is highly undesirable. For instance,
       if Solve returns an answer such as

            {{x -> 3}}

       then it will now be presented as

             (x -> 3)

       which can cause a lot of confusion. I would suggest 
       eliminating this possibilility by adding the exclusion
       rule:

               FreeQ[t, Rule] === True

        to yield 
    
        Function[t,  MatrixQ[Unevaluated[t]] && (t =!= {{}} && 
                             FreeQ[t, Rule] === True), HoldAll]


(2).  Let:

         lis = { {}, {}, {}, {} ... }

      Some functions might generate output like this.
      This generates a BEEP when Mathematica tries to format
      it as a "Matrix". I can't think of a nice general way to 
      exclude such cases.


Cheers

Colin

-- 
Colin Rose 
tr(I)    -  Theoretical Research Institute
__________________________________________
colin at tri.org.au    http://www.tri.org.au/


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