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MathGroup Archive 2001

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Re: Re: Overriding Power

  • To: mathgroup at smc.vnet.net
  • Subject: [mg26966] Re: [mg26868] Re: Overriding Power
  • From: "Carl K. Woll" <carlw at u.washington.edu>
  • Date: Tue, 30 Jan 2001 03:38:17 -0500 (EST)
  • References: <94m9e5$3nu@smc.vnet.net> <94oh4k$ee1@smc.vnet.net> <200101260627.BAA18659@smc.vnet.net> <6SJc6.6841$nn4.184149@ralph.vnet.net> <frumple*NOSPAM*-65C139.12194828012001@news>
  • Sender: owner-wri-mathgroup at wolfram.com

Jeff,

Ok, I didn't want to mention this possibility before, as it is a bit risky.
However, I tried it, and it seems to work.

Find the file UnicodeCharacters.tr. In my Windows installation, it can be
found in the directory:

Program Files\Wolfram
Research\Mathematica\4.0\SystemFiles\FrontEnd\TextResources

If you take a look at the contents of this file, you will find information
listed for each character that can be entered into Mathematica. In
particular, you should look for the entry under the operators you are
interested in, such as \[Wedge], which includes the precedence of that
operator. For example, the precedence of \[Wedge] is 560, and the precedence
of \[CircleDot] is 605. If you change the 560 to 607, then restart
Mathematica, you will find that the input

a \[CircleDot] b \[Wedge] c

will be interpreted as a \[CircleDot] (b \[Wedge] c), showing that on input,
\[Wedge] does have higher precedence. On the other hand, the printed output
obviously still considers \[CircleDot] to have higher precedence than
\[Wedge], as is evidenced by the paranthesis. I haven't investigated how to
change this, although PrecedenceForm may be the way to do so. Of course,
before you make any changes to this file, you should probably save an old
copy somewhere just in case you accidentally render it, and Mathematica,
unuseable. Also, it doesn't appear that you can change the precedence of the
operators which have built in meanings, like +,.,*, etc., as they are not
included in UnicodeCharacters.tr.

Good luck.

Carl Woll
Physics Dept
U of Washington

----- Original Message -----
From: "Jeff Hersh" <frumple*NOSPAM* at home.com>
To: mathgroup at smc.vnet.net
Subject: [mg26966] Re: [mg26868] Re: Overriding Power


> Carl,
>
> The problem is that I am trying to mimic the standard notation that is
> used for Geometric Algebra. The precedence is as follows...
>
> Outer Products (designated by \[Wedge])
> Inner Products (designated by \[Dot])
> Commutator and Scalar Products (designated by \[CircleTimes] and
> \[CircleDot] respectfully).
> Geometric Product (designated by white space, i.e. \[Times]).
>
> I know you can force different parethesiation via PrecedeceForm for
> individual items but this doesn't seem to work in general.
>
> Jeff
>
>
> In article <6SJc6.6841$nn4.184149 at ralph.vnet.net>, Carl Woll
> <carlw at u.washington.edu> wrote:
>
> > Jeff,
> >
> > I don't know how to change the precedence of a function, but why don't
> > you use
> > a built in operator which already has the precedence you want. For
> > example, if
> > you want to have a function whose precedence is greater than
> > NonCommutativeMultiply, you could look up in help for precedence, which
> > will
> > lead you to section A.2.7. Section A.2.7 contains a list of the
> > precedences of
> > all the built in operators. You will see that there are two built in
> > operators,
> > SmallCircle and CircleDot which carry a higher precedence than
> > NonCommutativeMultiply and which have no built in definitions. Hence, we
> > have
> >
> > a**b\[SmallCircle]c//FullForm
> >
> > NonCommutativeMultiply[a, SmallCircle[b, c]]
> >
> > Since SmallCircle has no built in definitions, simply give it the
> > definitions
> > you want.
> >
> > Carl Woll
> > Physics Dept
> > U of Washington
> >
> > Jeff Hersh wrote:
> >
> > > In article <94oh4k$ee1 at smc.vnet.net>, Roland Franzius
> > > <Roland.Franzius at uos.de> wrote:
> > >
> > > > Jeff Hersh wrote:
> > > >
> > > > > I am working on a package that deals with non-communative
> > > > > multiplication
> > > > > and I have run into a problem with the Power function. As we know
> > > > > Power[a b,n] (where n is an integer) automatically gets converted
> > > > > to
> > > > > Power[a,n] Power[b,n]. However, with non-communative
multiplication
> > > > > (I
> > > > > have removed the Orderless attribute from Times to make it
> > > > > non-communative) this isn't valid. Is there any way I can stop
> > > > > Mathematica from automatically doing this conversion?
> > > >
> > > > Hi Jeff,
> > > > I recommend to avoid overloading the existing algebraic functions
> > > > with
> > > > arguments  from a noncommutive algebra. Write your own functions and
> > > > use
> > > > Format for pretty printing the results. Especially for Power, Exp
> > > > there
> > > > are MatrixPower, MatrixExp which have build  features you are
> > > > requiring.
> > > >
> > > > regards, Roland
> > >
> > > In that case does anyone know how to change the precedence of a
> > > function
> > > so it is parenthesied correctly?  In other words I want the power
> > > function to have the same precedence as Power.
> > >
> > > Jeff
> > > --
> > > Jeffrey Hersh,PhD
> > >
> > > Remove the *NOSPAM* to reply.
> > >
> > > <insert amusing quote here>
> >
> >
> >
> --
> Jeffrey Hersh,PhD
>
> Remove the *NOSPAM* to reply.
>
> <insert amusing quote here>



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