On Sat, 15 Jul 2017 00:06:29 +0430, esarcush esarcush <esarcush@gmail.com> said:
EE> On 7/15/17, esarcush esarcush <esarcush@gmail.com> wrote: >> Agreement: Every dummy index have a hidden sigma. >> >> Based on the page you linked (and in common also), there are two >> ways to illustrate a dummy index in a term: 1) "j" is a dummy one >> iff it appears as superscript and subscript. >> >> 2) "j" is a dummy one iff it appears in two (or more that two) >> tensor coefficients making that term. >> >> GiNaC is using second approach. This makes some troubles to >> somebodies that are using first one. For example, I'd like to >> deal with some tensorials that have in-common indices as >> e.g. subscripts but free (as mentioned example). I think second >> approach is more physical vs first one more diff-geometrical. ;) Did you notice the existence of GiNaC::idx and GiNaC::varidx classes? For the first case you need to use varidx. -- Vladimir V. Kisil http://www.maths.leeds.ac.uk/~kisilv/ Book: Geometry of Mobius Transformations http://goo.gl/EaG2Vu Software: Geometry of cycles http://moebinv.sourceforge.net/ >> >> All the best, Esa >> >> >> >> >> >> >> >> >> On 7/14/17, Vladimir V. Kisil <kisilv@maths.leeds.ac.uk> wrote: >>>>>>>> On Fri, 14 Jul 2017 22:54:35 +0430, esarcush esarcush >>>>>>>> <esarcush@gmail.com> said: >>> EE> Dear all, in expression >>> EE> { indexed(A, i, j) * indexed(B, j, k) } >>> EE> GiNaC is saying that the dummy index is "j" and "i, k" are EE> free. Is there a way to determine dummy indices based on EE> Einstein summation notation; namely all the indices in the EE> latter be free. >>> >>> My understanding of >>> >>> https://en.wikipedia.org/wiki/Einstein_notation >>> >>> is that in the above expression there is summation over j, thus >>> it is not free. >>> -- >>> Vladimir V. Kisil http://www.maths.leeds.ac.uk/~kisilv/ Book: >>> Geometry of Mobius Transformations http://goo.gl/EaG2Vu >>> Software: Geometry of cycles http://moebinv.sourceforge.net/ >>> >> EE> _______________________________________________ GiNaC-list EE> mailing list GiNaC-list@ginac.de EE> https://www.cebix.net/mailman/listinfo/ginac-list