`characteristic_ff'
-------------------

characteristic_ff()
     :: Characteristic of the current base field.

RETURN
     integer

   * Returns the characteristic of the current base field.

   * P is returned if GF(P), where P is a prime, is set.  2 is returned
     if GF(2^N) is set.

     [0] characteristic_ff();
     characteristic_ff : current_ff is not set
     return to toplevel
     [0] setmod_ff(3);
     3
     [1] characteristic_ff();
     3
     [2] setmod_ff(x^2+x+1);
     x^2+x+1
     [3] characteristic_ff();
     2

References
     *Note `setmod_ff': setmod_ff

