Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2004
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2004

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Summation limits

  • To: mathgroup at smc.vnet.net
  • Subject: [mg46664] Re: Summation limits
  • From: Paul Abbott <paul at physics.uwa.edu.au>
  • Date: Fri, 27 Feb 2004 02:57:58 -0500 (EST)
  • Organization: The University of Western Australia
  • References: <c1lu5g$nse$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

In article <c1lu5g$nse$1 at smc.vnet.net>, tinkham at ucalgary.ca (tinkham) 
wrote:

> 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,

   With[{k=5,p=2},Sum[i,{i,1,k}]]

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 
palette.

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. 
See

   http://physics.uwa.edu.au/pub/Mathematica/MathGroup/TestSumIterator.nb

Cheers,
Paul

-- 
Paul Abbott                                   Phone: +61 8 9380 2734
School of Physics, M013                         Fax: +61 8 9380 1014
The University of Western Australia      (CRICOS Provider No 00126G)         
35 Stirling Highway
Crawley WA 6009                      mailto:paul at physics.uwa.edu.au 
AUSTRALIA                            http://physics.uwa.edu.au/~paul


  • Prev by Date: Re: fill the empty spaces in a matrix
  • Next by Date: Draws from Multivariate Normal Distribution
  • Previous by thread: Summation limits
  • Next by thread: Re: Summation limits