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MathGroup Archive 1998

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Re: D[Xc, X] = Nonsense ?



Kowald wrote:
> 
> Hello,
> 
> I'm using Mathematica 3 on a NT4 machine and I tried to use the new nice
> subscripts for naming my variables.
> I have a variable Xc (that's X subscript c) and a variable X which are
> non-identical. If I now try
> D[Xc ,X]     I get  Subscript(1,0) [X,c]  instead of zero.  If I type
> D[Xc ,Y]  everything is okay.
> So somehow Mathematica gets confused about the subscript. Does this mean
> I cannot have variables whose only difference is a subscript ?   Or
> what else is going on ?
> 
> Many thanks

Axel,
You need to use Utilities`Notation` - details in following notebook.



-- 
Allan Hayes
Training and Consulting
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hay@haystack.demon.co.uk
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Notebook[{

Cell[CellGroupData[{
Cell[BoxData[
    \(D[x\_c, x]\)], "Input"],

Cell[BoxData[
    RowBox[{
      SuperscriptBox["Subscript", 
        TagBox[\((1, 0)\),
          Derivative],
        MultilineFunction->None], "[", \(x, c\), "]"}]], "Output"] },
Open  ]],

Cell[CellGroupData[{

Cell[BoxData[
    \(FullForm[x\_c]\)], "Input"],

Cell[BoxData[
    TagBox[
      StyleBox[\(Subscript[x, c]\),
        ShowSpecialCharacters->False,
        ShowStringCharacters->True],
      FullForm]], "Output"]
}, Open  ]],

Cell["Is treated exacly the same as g[x,c]:", "Text"],

Cell[CellGroupData[{

Cell[BoxData[
    \(D[g[x, c], x]\)], "Input"],

Cell[BoxData[
    RowBox[{
      SuperscriptBox["g", 
        TagBox[\((1, 0)\),
          Derivative],
        MultilineFunction->None], "[", \(x, c\), "]"}]], "Output"] },
Open  ]],

Cell["We need to make Subscript[x,c] into a symbol:", "Text"],

Cell["<< \"Utilities`Notation`\"", "Input"],

Cell[BoxData[
    RowBox[{"Symbolize", "[", 
      TagBox[\(x\_c\),
        NotationBoxTag,
        Editable->True], "]"}]], "Input"],

Cell[CellGroupData[{

Cell[BoxData[
    \(D[x\_c]\)], "Input"],

Cell[BoxData[
    \(x\_c\)], "Output"]
}, Open  ]],

Cell["\<\
You can find out about Notation in
\tMathematica 3.0 \
Files/AddOns/ExtraPackages/Utilities/Documentation/English/\
NotationDocumentation.nb
and
Files/AddOns/ExtraPackages/Utilities/Documentation/English/Other \
Information/NotationExamples.nb

and get the latest versions from
          http://wolfram.com/~jasonh/\ \>", "Text"]
},
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ScreenRectangle->{{0, 1152}, {0, 850}}, WindowSize->{520, 740},
WindowMargins->{{Automatic, 283}, {20, Automatic}},
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00`0001804P000000bX2@?oaooL3>@99:P85N0?N0@00004/0B`000003Bl9H001
0000I0000@400@0000000BL?0040000000000000000000000000000000000?o2
omX=K@V600P100000000000000000000\>"
]


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Cell[2042, 67, 164, 5, 38, "Output"] }, Open  ]],
Cell[2221, 75, 53, 0, 30, "Text"],

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"Output"] }, Open  ]],
Cell[2897, 109, 339, 11, 158, "Text"] }
]
*)



(***********************************************************************
End of Mathematica Notebook file.
***********************************************************************)



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