Using subscripted symbols in functions

Question

Using subscripts would significantly improve the structure of my code. Until now I used the following two lines to implement this.

Needs["Notation`"];
Symbolize[ParsedBoxWrapper[SubscriptBox["_", "_"]]];

This allows me to define a symbol like

Subscript[a, r] = 10

This works fine up to the point where I want to define e.g.

f[r_] = r Subscript[a, r][r]

I want the result to be

f[x] = 10 x

The problem is that Mathematica recognizes the r in Subscript[a, r] as an variable. Hence I can not use the subscript in such a case. Is there an easy way to solve this?

My experience tells me that you will disappointed with the approach you are taking -- introducing subscripted variables will cause more problems than improvements to the structure of your code. — m_goldberg, Jul 21 '15 at 13:51

m_goldberg · Answer 1 · 2015-07-21T13:47:45.353

1

I think you may want

With[{u = Subscript[a, r]}, f[r_] := u r]

then

f[x]

10 x

Or perhaps you want to keep Subscript[a, r] as a free variable.

g[x_] := Subscript[a, r] x
g[x]

10 x

Subscript[a, r] = 42; g[x]

42 x

edited Jul 21 '15 at 13:47

answered Jul 21 '15 at 13:35

m_goldberg

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Using subscripted symbols in functions

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