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Re: Precedence question

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Well, I just learned from Mark (author of DesignerUnits 
package  http://designerunits.com/)
a much better precedence adjusting solution.
Study that package for details (not an easy task).

Sincerely, Arturas




On Sat, 28 May 2011, Arturas.Acus@tfai.vu.lt wrote:

> Following David's suggestion I wrote the following
> function
>
> myPreFunction[{x},ReplaceAll[ToExpression[StringReplace[ToString[x],{"\[Wedge]"->"\[CircleDot]","\[CenterDot]"->"\[SmallCircle]"}],StandardForm],{CircleDot->Wedge,SmallCircle->CenterDot}],{HoldAll}]
>
> which seems do the job.
>
> However I notice that if the following function
>
>
> $PreFunction[{x},ReplaceAll[ToExpression[StringReplace[ToString[x],
> {"\[CenterDot]"->"\[SmallCircle]","\[Wedge]"->"\[CircleDot]"}]],{SmallCircle->>CenterDot,CircleDot->Wedge}],{HoldAll}]
>
>
> is evaluated inside package private context (package context impors Global`)
> I encounter the problems (for example FullForm do not work properly).
>
> I think this function should be evaluated in the very beginning, however
> I have no idea how to include it into package structure. (init.m ?)
>
>
>
>
> David Bailey <dave@removedbailey.co.uk> ra=C5=A1=C4=97:
>
>> On 25/05/2011 10:57, Arturas.Acus@tfai.vu.lt wrote:
>>>
>>> Dear Group
>>> In order to implement some geometric algebra code I need
>>> to reverse the order of the following operators which have no built in
>>> meaning:
>>>
>>> Precedence/@{NonCommutativeMultiply,Wedge,CenterDot}
>>>
>>> Acording to geometric algebra rules the highest precedence has inner
>>> product operator =C2 (I plan to use CenterDot symbol to denote this),
>>> then goes Wedge (outer multiplication) and last is geometric product
>>> (will definetely use NonCommutativeMultiply for that)
>>>
>>> Because of Mathematica predefined precedences the following input
>>>
>>> MV[a]\[Wedge]MV[b]\[CenterDot]MV[c]**MV[d]//FullForm
>>>
>>> is interpreted as
>>>
>>> CenterDot[Wedge[MV[a],MV[b]],NonCommutativeMultiply[MV[c],MV[d]]]
>>>
>>> whereas I need
>>>
>>> NonCommutativeMultiply[Wedge[MV[a],CenterDot[MV[b],MV[c]]],MV[d]]]
>>>
>>>
>>> Few hours of Mathematica documentation reading did not yield any simple solution.
>>>
>>> Sure, instead of operators with no build in meaning I can use symbols
>>> with user precedence level =C2 ( for example =C2 \[RawWedge] instead of
>>> \[Wedge]).
>>> =C2  The problem then is to define proper Infix INPUT notation+ alias.
>>> This can be done with Notation package, hovewer this is what I would
>>> like to avoid, because the task becomes complicated from the very
>>> begining.
>>>
>>>
>>> Could anybody suggest more simple alternative?
>>>
>>>
>>> Sincerely, Arturas Acus
>>>
>>
>> One possible approach would be to supply your expressions as strings,
>> and then use StringReplace to replace the operator characters with
>> another set with the correct order of precedences (and no built-in
>> meaning). Then you could use ToExpression on the result, and work from
>> there.
>>
>> David Bailey
>> http://www.dbaileyconsultancy.co.uk
>>
>>
>
>

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Re: Precedence  question Arturas Acus <Arturas.Acus@tfai.vu.lt> - 2011-05-29 11:36 +0000

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