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