Re: Readability confuses mathematica?

*To*: mathgroup at smc.vnet.net*Subject*: [mg44565] Re: Readability confuses mathematica?*From*: Jason Harris <jasonh at wolfram.com>*Date*: Fri, 14 Nov 2003 04:43:12 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

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

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**Re: Readability confuses mathematica?**

**Re: Readability confuses mathematica?**