• To: mathgroup at smc.vnet.net
• Subject: [mg44531] Re: Readability confuses mathematica?
• From: "John Jowett" <John.Jowett at cern.ch>
• Date: Thu, 13 Nov 2003 05:57:49 -0500 (EST)
• Organization: CERN
• References: <botcm2\$ci7\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```This is one of the cases where traditional mathematical notation is
inconsistent, relying on the reader's knowledge of the context:  x_i (I mean
x with a subscript i) might mean the i th component of x, while x_0 means an
initial condition.  How does one know what x_1 means ?

Since Mathematica like to be consistent you have to give it a little more
information.   Beginners in traditional mathematics often have the same
problem until they get used to the customary illogicality of the notations
used in particular areas.

Anyway, Mathematica's Notation package allows x_0 to be treated as a
compound symbol.

John Jowett

"patrick_m_lahey" <patrick.m.lahey at aero.org> wrote in message
news:botcm2\$ci7\$1 at smc.vnet.net...
> I am new to mathematica so perhaps there is a simple answer to this
>
> Consider:
>
> In[1]:= D[x-x0,x]
>
> except that x0 is really x ctrl-- 0 (x subscript 0).  Normally that
> would be a completely independent variable from x but not according to
> mathematica!
>
> Out[1]=1-Subscript(1,0)[x,0]
>
> (the (1,0) is a superscript of Subscript).
>
> One of the things that attracted me to mathematica was the ability to
> work with expressions that closely mirrored the true expressions of
> interest (a readability issue really...).
>
> Is there anything that can be done here?
>

```

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