Re: How to delay action of ...[[i]] (Part[...,i])

*To*: mathgroup at smc.vnet.net*Subject*: [mg112319] Re: How to delay action of ...[[i]] (Part[...,i])*From*: ADL <alberto.dilullo at tiscali.it>*Date*: Thu, 9 Sep 2010 04:22:47 -0400 (EDT)*References*: <i6759o$8ct$1@smc.vnet.net>

I think that the original issue posted by Scott exposes a Mathematica limitation, mentioned by Wolfram himself (http://blog.wolfram.com/ 2009/11/12/the-rd-pipeline-for-mathematica/), which is the difficulty of dealing in Mathematica with general indexed structures (vectors and tensors). In other terms, the notation used to write equation in physics/ engineering books cannot be directly fed into Mathematica and the path from equations to computations is quite more cumbersome than what one might wish (given the symbolic nature of the tool). The error message provided by Mathematica when writing x[[i]] with x a symbol, is just the tip of an iceberg. Wolfram said that this issue was solved: "Well, the exciting thing we have coming in the pipeline is fully integrated tensors.". Let us see what happens with version 8... ADL