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Re: Summation limits

  • To: mathgroup at
  • Subject: [mg46664] Re: Summation limits
  • From: Paul Abbott <paul at>
  • Date: Fri, 27 Feb 2004 02:57:58 -0500 (EST)
  • Organization: The University of Western Australia
  • References: <c1lu5g$nse$>
  • Sender: owner-wri-mathgroup at

In article <c1lu5g$nse$1 at>, tinkham at (tinkham) 

> I want to do a summation, using the symbol form from clicking on the
> palette button, but want to put a test on the index of the iterator.
> for example, I will have global variables, k=5 and p = 2, and want to
> do a summation from i=1 to k, where i != p. How do I enter the lower
> limit i=1;i!=p  ? 

You cannot put a test on the index of the iterator because iterators do 
not permit this, independent of the form of input. For example,


is, of course, ok. And, if you convert this input to StandardForm (or 
TraditionalForm) you get the same 2D form as you would get from a 

However, there is AFAIK, no way to modify the _iterator_ of 
Sum[i,{i,1,k}] to include a test.
> I realize that I can just wrap the expression being summed in an
> If[i!=p, ...], but it would be nice if I could just put this test in
> the lower limit.

There is a way to do this: use the Notation package to define your own 
input notation that accepts a lower limit of the form, say i != 1 = p. 


Paul Abbott                                   Phone: +61 8 9380 2734
School of Physics, M013                         Fax: +61 8 9380 1014
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