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Help with custom Format

  • To: mathgroup at
  • Subject: [mg8456] Help with custom Format
  • From: Ersek_Ted%PAX1A at
  • Date: Sat, 30 Aug 1997 00:43:10 -0400
  • Sender: owner-wri-mathgroup at

Hello Math Group,
Consider the following:

In[1]:= poly=2+a*x+b*x+z*x^2+y*x^2+e*x^3+d*x^3 ;

In[2]:= Collect[poly, x]

Out[2]= 2 + (a+b) x + (d+e) x^3 + x^2 (y+z)

I want to change Collect so the result is displayed in a non-standard order.
In particular I want the Output above to show as follows:

Out[2]= 2 + (a+b) x + (y+z) x^2 + (d+e) x^3

The tricky part is that I don't want anything like HoldForm to show-up in 
the FullForm of the  result.  The reason is that I want to be able to use 
the result later on without making use of ReleaseHold[] or anything like 
that.  This way the use of the format I prefer will be transparent to the 

I did figure out how to make a function I call "TemporaryHold" that helps 
get the results I want.  A few months ago I discussed in the mathgroup my 
work with TemporaryHold.

However, I think it's better to use a custom Rule for MakeBoxes to do what I 
The problem is that after Collect is done with poly, the FullForm looks the 
same as it does for any other polynomial.  Now I don't know how I can only 
use my custom Rule for expressions that come from Collect[], but not for 
other expressions.

I think   InterpretationBox[boxes, expr]
was made for this sort of thing.  But I don't understand how to use it.

Any solutions greatly appreciated.

     Ted Ersek

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