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MathGroup Archive 2003

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Re: Readability confuses mathematica?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg44574] Re: Readability confuses mathematica?
  • From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
  • Date: Sat, 15 Nov 2003 02:05:04 -0500 (EST)
  • References: <p05200f03bbda31b43753@[192.168.0.101]>
  • Sender: owner-wri-mathgroup at wolfram.com

I am afraid it is not going to be that simple. It seems that my 
repeated attempts to use Symbolize caused me to enter the 
NotationBoxTag wrapper twice, but this is a red herring and has nothing 
to do with the problem. (It is actually rather unlikely that I would 
have the habit of entering this tag twice. It was just one of those 
unlikely coincidences that keep happening, that when I decide to post 
the error to the MathGroup this kind of thing happens which obscures 
the whole problem.)

In any case, the point is that with only a fresh kernel and only the 
following input:

In[1]:=
<<Utilities`Notation`

In[2]:=
Cell[BoxData[
     RowBox[{"Symbolize", "[",
       TagBox[
         SubscriptBox["x", "_"],
         NotationBoxTag,
         TagStyle->"NotationTemplateStyle"], "]"}]], "Input",
   CellLabel->"In[2]:="]

whcih you can now see is quite correct I still get:


In[3]:=
\!\(f[\(x\_1\) : _] := x\_1\^2\)

 From In[3]:=
\!\(\*FormBox[
   RowBox[{\(Syntax::"sntxf"\), \(\(:\)\(\ \)\), \
"\<\"\\\"\\!\\(TraditionalForm\\`\\(f[\\)\\)\\\" cannot be
       followed by \\\"\\!\\(TraditionalForm\\`\\(\\(\\(x\\_1 : 
_\\)\\)]\\)\\)\
\\\".\\!\\(TraditionalForm\\`\\\"\\\"\\) 
\\!\\(\\*ButtonBox[\\\"More?\\\", \
ButtonStyle->\\\"RefGuideLinkText\\\", ButtonFrame->None, \
ButtonData:>\\\"General::sntxf\\\"]\\)\"\>"}], TraditionalForm]\)

 From In[3]:=
\!\(\*
   StyleBox[
     RowBox[{
       RowBox[{"f", "[",
         ErrorBox[\(\(x\_1\) : _\)], "]"}], ":=", \(x\_1\^2\)}],
     ShowStringCharacters->True]\)

Andrzej


On 14 Nov 2003, at 16:23, Jason Harris wrote:

> Hi Andrzej,
>
> [Notation example snipped]
>
>>  On my system this example just fails miserabley (the
>>  definiton of transmissionCoefficient does not parse) although it once
>>  used to work. (Actually, I would like to hear from other people,
>>  because either the Notation package is no longer working or something
>>  is wrong with my installation).
>
> I know these things can appear frustrating at times, but the Notation
> package is working fine. In the example you have given, you have
> managed to include the box wrapper twice in your Symbolize statement.
> (You likely did this through copying the k subscript including box
> wrapper and pasted it into a new Symbolize statement.)
>
>
>>  Anyway, if this works on your system than the problem is solved. You
>>  can symbolize subscripted variables and use them as if they were
>>  symbols. On the other hand, in the past, when this package used to 
>> work
>>  on my system, I got myself into a huge mess when I tried to evaluate
>>  again a notebook that had previously worked correctly.
>
> If there is some notebook corruption going on then we definitely want
> to know about this. In the example you have given it is extremely
> likely that you inadvertently caused the error with a copy and paste
> from one symbolize statement to another. (I know notation statements
> can be tricky and it is not all that hard to "hang yourself".)
>
>
>>  Because of that I finally decided that relying on a package like 
>> this is
>>  just too risky if you are doing any serious work.
>
> Hmm... Actually I personally think its just the opposite. If you are
> really doing serious work you need to know about typesetting and how
> to enter expressions in notations which are familiar to
> Mathematicians, physicists, and other users and have these notations
> function correctly.
>
> First a general comment:
> When you are troubleshooting problems with setting up notations it is
> often necessary to look at the underlying boxes representing the
> typeset expression. You can do this through either the command key
> shortcut of cmd-shift-E (OSX) and I think cntrl-shift-E (Win), or
> through the menu item "Format" -> "Show Expression..."
>
> Looking at the underlying boxes shows you how the typeset expression
> is represented. As a Mathematica programmer you no doubt use FullForm
> at times to examine how a certain pattern is structured. Its really
> not too different with typesetting in that Mathematica functions 
> through
> MakeBoxes and MakeExpression which operate on these box structures. If
> you don't have the correct structures, the boxes will not be
> interpreted as they should be.
>
> In a Symbolize statement waiting to be filled in the underlying
> structure is
>
> Cell[BoxData[
>     RowBox[{"Symbolize", "[",
>       TagBox["\[Placeholder]",
>         NotationBoxTag,
>         TagStyle->"NotationTemplateStyle"], "]"}]], "Input"]
>
> To see this load the notation package, type Esc-symb-Esc and then show
> the underlying expression. The box structure to be symbolized must be
> the first argument of this TagBox.
>
> The tag box wrapper, NotationBoxTag, is necessary so you can enter
> typeset expressions into Mathematica that are not currently
> syntactically valid. Then once the Notation package gets a hold of
> them, it compiles / translates these into corresponding rules for
> MakeExpression and MakeBoxes that do what you instructed. The tag box
> wrapper inertizes the box structure so it becomes syntactically valid
> Mathematica input.
>
> You can see this by copying out the box wrapper into a new cell and
> entering some syntactically invalid input into the wrapper, say "x"
> followed by "*", and then viewing how it is interpreted by
> Mathematica. E.g. after loading the notation package paste the
> following cell into Mathematica and interpret it:
>
> Cell[BoxData[
>     TagBox[
>       RowBox[{"x", "*"}],
>       NotationBoxTag,
>       TagStyle->"NotationTemplateStyle"]], "Input"]
>
> Then evaluate this interpreted cell. Then start a new cell and
> evaluate FullForm[%]. The answer will be
>
> NotationBoxTag[RowBox[List["x", "*"]]]
>
> Thus the TagBox wrapper, NotationBoxTag, has allowed us to enter
> something that is syntactically invalid and get the box structure into
> the kernel. (Incidentally you can programmatically create symbolize
> and notation statements this way.) The TagBox wrapper NotationBoxTag
> can do this miraculous feat because it itself has a corresponding
> notation. (The TagStyle option is set so you can get some visual
> indication of where these tag box wrappers occur.)
>
> So anyway getting back to your example if you look at the underlying
> boxes you will see that instead of having
>
> Cell[BoxData[
>     RowBox[{"Symbolize", "[",
>       TagBox[
>         SubscriptBox["k", "_"],
>         NotationBoxTag,
>         TagStyle->"NotationTemplateStyle"], "]"}]], "Input"]
>
> You had
>
> Cell[BoxData[
>     RowBox[{"Symbolize", "[",
>       TagBox[
>         TagBox[
>           SubscriptBox["k", "_"],
>           NotationBoxTag,
>           TagStyle->"NotationTemplateStyle"],
>         NotationBoxTag,
>         TagStyle->"NotationTemplateStyle"], "]"}]], "Input"]
>
> i.e. the wrapper was in there twice. Fixing this mistake resolves your 
> problem.
>
> Cheers,
>   Jason
>
> -------------
> Jason Harris
> Wolfram Research
>
>
Andrzej Kozlowski
Yokohama, Japan
http://www.mimuw.edu.pl/~akoz/


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