5.1.112 rvar
------------
Syntax:
rvar ( name )

rvar ( poly_expression )

rvar ( string_expression )
Type:
int
Purpose:
returns the number of the variable if the name is a ring variable of the
basering or if the string is the name of a ring variable of the
basering; returns 0 if not. Hence the return value of rvar can
also be used in a boolean context to check whether the variable exists.
Example:
  ring r=29,(x,y,z),lp;
  rvar(x);
==> 1
  rvar(r);
==> 0
  rvar(y);
==> 2
  rvar(var(3));
==> 3
  rvar("x");
==> 1
See
defined;
ring;
var;
varstr.
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&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; User manual for <a href="http://www.singular.uni-kl.de/"><i>Singular</i></a> version 2-0-4, October 2002,
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