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MathGroup Archive 2001

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Re: What variables are in a function and displaying surds

  • To: mathgroup at smc.vnet.net
  • Subject: [mg31123] Re: [mg31117] What variables are in a function and displaying surds
  • From: BobHanlon at aol.com
  • Date: Fri, 12 Oct 2001 03:36:40 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

In a message dated 2001/10/10 7:58:27 PM, michael_r_went at yahoo.com writes:

>Is there a way in Mathematica to generate a list of variables in an
>expression like Variable[]. For example if I passed the expression
>Sin[x+y]+ z/p - t the list {x,y,z,p,t} would be generated.
>

expr=Sin[x+y]+z/p-t+Pi-E;

Cases[expr, _Symbol, Infinity]

{E, Pi, t, p, z, x, y}

Note that Pi and E are symbols.  To exclude numeric symbols:

Cases[expr, _Symbol?(!NumericQ[#]&), Infinity]

{t, p, z, x, y}


Bob Hanlon
Chantilly, VA  USA


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