在 Mathematica 中定义自定义符号

您可以使用 Action -> 查看底层的 NotationMake* 下值构造.PrintNotationRules 选项.在[4]中截图生成NotationMakeExpression[SubscriptBox[vals_, RowBox[{vars_, "|", svars_}]], StandardForm] :=MakeExpression[RowBox[{"restrict", "[", RowBox[{vars, ",", svars, ",", vals}],]}]， 标准格式]NotationMakeBoxes[下标[vals_, vars_ |svars_], StandardForm] :=SubscriptBox[MakeBoxes[vals, StandardForm],RowBox[{Parenthesize[vars, StandardForm, Alternatives], "|",括号[svars, StandardForm, Alternatives]}]]I often need to extract to restrict value lists to sublists, ie if vals gives values of vars={x1,x2,x3,x4}, and I need values of svars={x2,x4} I do restrict[list,vars,svars] whererestrict[vars_, svars_, vals_] := Extract[vals, Flatten[Position[vars, #] & /@ svars, 1]]I'd like to improve code readability, perhaps by defining following custom notation for restrict[vars,svars,vals]My questions areWhat is a good way to implement this?Is this a good idea altogether? 解决方案 Good notations can be very useful - but I'm not sure that this particular one is needed...That said, the Notation package makes this pretty easy. As there are many hidden boxes when you use the Notation palette, I'll use a screenshot:You can see the underlying NotationMake* downvalues construct by using the Action -> PrintNotationRules option. In[4] in the screenshot generatesNotationMakeExpression[ SubscriptBox[vals_, RowBox[{vars_, "|", svars_}]], StandardForm] := MakeExpression[ RowBox[{"restrict", "[", RowBox[{vars, ",", svars, ",", vals}], "]"}], StandardForm]NotationMakeBoxes[Subscript[vals_, vars_ | svars_], StandardForm] := SubscriptBox[MakeBoxes[vals, StandardForm], RowBox[{Parenthesize[vars, StandardForm, Alternatives], "|", Parenthesize[svars, StandardForm, Alternatives]}]] 这篇关于在 Mathematica 中定义自定义符号的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 上岸，阿里云！