taking polynomials modulo integer

[bil@beeb.net]

Hi,
I've not had much experience using gp as yet, but think it's very good.
I now have a problem for which I haven't been able to figure out the
right magic words...
I have a polynomial and wish to square it and take the result modulo
an integer. For example:

	f = x + x^3 + x^7 + x^11

	Mod(f^2, 13)

gives an error message:

  ***   forbidden division t_POL % t_INT.

I need something that will use Fermat's Little Theorem to reduce
the powers to be within the range of the modulus, 
i.e. (x^11)^2 = x^22 == x^10 (mod 13) { using == for congruence symbol}

Can anyone point me at the right function to apply?

Many thanks,

Bill
-- 
+---------------------------------------+
| Bill Purvis, Amateur Mathematician    |
|  email: bil@beeb.net                  |
|  http://bil.members.beeb.net          |
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