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Re: Subscript in parameter names

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  • Subject: [mg128525] Re: Subscript in parameter names
  • From: Bill Rowe <readnews at>
  • Date: Sun, 28 Oct 2012 01:56:21 -0400 (EDT)
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On 10/26/12 at 11:47 PM, per at RQNNE.invalid (Per R=C3=B8nne) wrote:

>You define functions in Mathematica like this:

>c[a_, b_]:= ^2a^6+b^6

>Giving Sqrt[a^2+b^2]

>But how will you define a function with a parameter with a
>subscript, like

>L[L^_0^ _,v]:=L^_0*^21-^/v^6 c^6

>Giving L[L0,v]:= L0*Sqrt[1-v^2/c^2]

>Except that L0 should be with a real subscript.

>In this example, c is 299,792,458 m/s, L0 the proper length in the
>velocity direction of an object with speed v relative to the
>observed lenght L from an intertial system with speed 0.

It is possible to use subscripted variables in Mathematica. To
do so, load the Notation package and make use of the function
Symbolize, But subscripts simply are not allowed in parameter
names. To partially get the result you seem to want, you can do:

In[1]:= << Notation`

In[1]:= Symbolize[Subscript[L, 0]];
L[x_, v_] := x*Sqrt[1 - v^2/c^2]

In[3]:= L[Subscript[L, 0], v]

Out[3]= Subscript[L, 0]*Sqrt[1 - v^2/c^2]

Note, Symbolize was entered using the palette that appears when
the Notation package is loaded and I've converted cells to input
form for email purposes. Frankly, I do not see using subscripted
variables as worth the required effort in Mathematica.

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