Re: Subscript in parameter names

• To: mathgroup at smc.vnet.net
• Subject: [mg128524] Re: Subscript in parameter names
• From: Bob Hanlon <hanlonr357 at gmail.com>
• Date: Sun, 28 Oct 2012 01:56:01 -0400 (EDT)
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• Delivered-to: l-mathgroup@wolfram.com
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• References: <20121027034731.0C53F687C@smc.vnet.net>

Needs["PhysicalConstants`"]

SpeedOfLight

(299792458*Meter)/Second

L[x_, v_] := x*Sqrt[1 - v^2/c^2]

L[Subscript[L, 0], v]

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

% /. {v -> 250000000. Meter/Second,
c -> SpeedOfLight}

0.5519000950955603*
Subscript[L, 0]

Bob Hanlon

On Fri, Oct 26, 2012 at 11:47 PM, Per R=F8nne <per at rqnne.invalid> 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.
> --
> Per Erik R=F8nne
> http://www.RQNNE.dk
> Errare humanum est, sed in errore perseverare turpe
>

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