Decimal comma on input

*To*: mathgroup at smc.vnet.net*Subject*: [mg60531] Decimal comma on input*From*: Cca <cca at gregosetroianos.mat.br>*Date*: Mon, 19 Sep 2005 04:45:48 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Here in Brazil our decimal separator is a comma. (This is the favoured convention in most non English-speaking countries.) We also put dots between each group of three digits. As an example, the number whose numeral is 1234.56789 in USA is represented in Brazil as NumberForm[1234.56789, DigitBlock->{3,3}, NumberPoint->",", NumberSeparator->"."] or also (following the SI) NumberForm[1234.56789, DigitBlock->{3,3}, NumberPoint->",", NumberSeparator->" "] This said, it is natutal to ask: how to instruct Mathematica to recognize a decimal comma on input? My ad hoc solution is shown below, but I would be very interested in knowing alternative approaches. --------------------------------------------- Instead of a "true" comma, I use one with hidden information, namely TagBox[",", Identity, Editable->False, SyntaxForm->"."] // DisplayForm with the following rule (which will work, of course, only in the expected contexts): MakeExpression[RowBox[{a_, TagBox[",", Identity, Editable->False, SyntaxForm->"."], b_}], form_] := MakeExpression[StringJoin[a, ".", b], form] Now we can try, for example, 2,3*3,5, 2,3+1,45, etc. --------------------------------------------- Finally, to make it easy to insert the decimal comma above I provide four ways to the user: (1) a button: ButtonBox[",", ButtonData-> TagBox[",", Identity, Editable->False, SyntaxForm->"."]// DisplayForm (2) a rule for InputAliases (which overrides \[InvisibleComma]); (3) a keyboard shortcut, for which I add the following line to the file KeyEventTranslations.tr: Item[KeyEvent["KeypadDecimal"], FrontEndExecute[ {FrontEnd`NotebookWrite[FrontEnd`InputNotebook[], TagBox[",", Identity, Editable->False, SyntaxForm->"."], After]}]] (4) a menu command (not well tested yet): LinkWriteHeld[$ParentLink, Hold@AddMenuCommands["New", {Item["Decimal comma", FrontEndExecute[{ FrontEnd`NotebookWrite[FrontEnd`InputNotebook[], TagBox[",", Identity, Editable->False, SyntaxForm->"."], After]}]]}]] --------------------------------------------- Carlos César de Araújo Gregos & Troianos Educacional www.gregosetroianos.mat.br Belo Horizonte, MG, Brazil (31) 3283-1122