Re: Q: Why can't I stop TraditionalForm dismissing Times Attributes ?

*To*: mathgroup at smc.vnet.net*Subject*: [mg15810] Re: [mg15736] Q: Why can't I stop TraditionalForm dismissing Times Attributes ?*From*: Andrzej Kozlowski <andrzej at tuins.ac.jp>*Date*: Sun, 7 Feb 1999 02:04:26 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

This is not really an explanation of the question about TraditionalForm you are asking. I think an explanation can probably only be given by a wri insider and would only be of interest to someone with particular concern with the Mathematica Front End. However, in general it should never be necessary (and is usually not a good idea) to change any attributes of Plus and Times. If you want your own non-listable versions you should simply define them. Here is an example: In[3]:= mytimes[x___,y_List,z___]:=Sequence[x,y,z]; mytimes[x__]:=Times[x]; myplus[x___,y_List,z___]:=Sequence[x,y,z]; myplus[x__]:=Plus[x]; Since I am not sure what you want to happen when one of the arguments to mytimes or myplus is a list I decided just to return a Sequence. Now the following thing will happen: In[25]:= mytimes[3,2,5] Out[25]= 30 In[26]:= mytimes[{3,4},5] Out[26]= Sequence[{3, 4}, 5] The advantage of using Sequence here is that if for some reason you want to you can immediately use the usual Times: In[27]:= Times[%] Out[27]= {15, 20} I do not think there are now any problems with TraditionalForm. The only weakness of this approach seems to me that you can't enter the new addition and multiplication as + or *. But even this can be fixed: In[28]:= <<Utilities`Notation` In[29]:= InfixNotation[+,myplus]; InfixNotation[*,mytimes]; (note that InfixNotation must be entered using the special Notation palette!) Now everything works as it always had In[30]:= Expand[(x+y)*(a+b)] Out[30]= a x + b x + a y + b y but In[31]:= {x,y}*{a,b} Out[31]= Sequence[{x, y}, {a, b}] On Fri, Feb 5, 1999, Fabien Boniver <F.Boniver at ulg.ac.be> wrote: >Hi, > >This message ends with the shortest transcript I can get of a session >explaining >my problem. >This is about two bizarre side-effects of TraditionalForm. Maybe they >are due to some (numerous 8-) ) lacks in my Mathematica knowledge. > >In order to do some formal computations, I need Plus and Times not to be > >Listable. See the myPlusTimes function below. TraditionalForm seems to >rely on the fact that Times is Listable (that would be another >transcript 8-) ) and it actually modifies the Listable property of >Times, which in turn leads to amazing results. > >So, I decided to try to be clear and precise (see function mathPlusTimes > >and myTraditionalForm below). >And now, Mathematica does not do the same thing on two consecutive >evaluations of the same computation (see In[7] and In[9]), though I >don't attempt to affect any symbol value. > >I use Mathematica 3.0.1.1x on a PMAC 604e running MacOs 8.1. > >Hope somebody can explain. >Many thanks in advance, > >Fabien > >*** CUT TRANSCRIPT HERE >In[1]:= >Attributes[{Plus,Times}] >Out[1]= >{{Flat,Listable,NumericFunction,OneIdentity,Orderless,Protected},{Flat, >Listable,NumericFunction,OneIdentity,Orderless,Protected}} > >In[2]:= >mathPlusTimes[dummy_]:=Module[{},Unprotect[Plus,Times]; >SetAttributes[Plus,Listable]; >SetAttributes[Times,Listable]; >Protect[Plus,Times]; >dummy >] > >In[3]:= >myPlusTimes[dummy_]:=Module[{},Unprotect[Plus,Times]; >ClearAttributes[Plus,Listable]; >ClearAttributes[Times,Listable]; >Protect[Plus,Times]; >dummy >] > >In[4]:= >myTraditionalForm[x_]:=myPlusTimes[TraditionalForm[mathPlusTimes[x]]] > >In[5]:= >myPlusTimes[1]; > >In[6]:= >Attributes[{Plus,Times}] >Out[6]= >{{Flat,NumericFunction,OneIdentity,Orderless,Protected},{Flat,NumericFun ction, > >OneIdentity,Orderless,Protected}} > >In[7]:= >1//myTraditionalForm >Attributes[{Plus,Times}] >Out[7]//TraditionalForm= >1 >Out[8]= >{{Flat,NumericFunction,OneIdentity,Orderless,Protected},{Flat,Listable, >NumericFunction,OneIdentity,Orderless,Protected}} > >In[9]:= >1//myTraditionalForm >Attributes[{Plus, Times}] >Out[9]//TraditionalForm= >1 >Out[10]= >{{Flat,NumericFunction,OneIdentity,Orderless,Protected},{Flat,NumericFun ction, > >OneIdentity,Orderless,Protected}} > >*** END OF TRANSCRIPT > > >-- >Fabien BONIVER > >Inst. of Math., University of Liege >** >Universite de Liege >Service de Geometrie et Theorie des Algorithmes Institut de >Mathematique, B37 >Grande Traverse, 12 >4000 Sart Tilman (Liege), Belgium >** >Email : F.Boniver at ulg.ac.be >Phone : + 32 4 366 94 17 > Andrzej Kozlowski Toyama International University JAPAN http://sigma.tuins.ac.jp/ http://eri2.tuins.ac.jp/