Re: Simplifying and Rearranging Expressions
- To: mathgroup at smc.vnet.net
- Subject: [mg96031] Re: Simplifying and Rearranging Expressions
- From: David Bailey <dave at removedbailey.co.uk>
- Date: Mon, 2 Feb 2009 06:20:34 -0500 (EST)
- References: <gls1u8$hjl$1@smc.vnet.net> <gm3rah$mga$1@smc.vnet.net>
John Doty wrote: > David Park wrote: > >> Nevertheless, even simple rearrangement can be difficult. I sometimes think >> of it as doing surgery on expressions. I believe it is generally desirable >> to use Mathematica to rearrange an expression and not retype the expression. >> Retyping is too error prone. > > In most cases, any description of how to rearrange an expression to a > specific form in a CAS will be more complex than a retyped expression. I > believe this is a theorem. > > Therefore, in most cases, the easiest way will be to retype. It's not > error prone if you check it, e.g.: > > Simplify[ retyped == original ] > Testing successive transformations in this way is useful, but not all transformations are exact. Particularly in physics, it is common to take a Taylor expansion of part of an expression, or maybe even change notation is some subtle way. David Bailey http://www.dbaileyconsultancy.co.uk