addAt(z, t, i+k)
		}

		putNat(tp)
	}

	return z.norm()
}

// basicSqr sets z = x*x and is asymptotically faster than basicMul
// by about a factor of 2, but slower for small arguments due to overhead.
// Requirements: len(x) > 0, len(z) == 2*len(x)
// The (non-normalized) result is placed in z.
func basicSqr(z, x nat) {
	n := len(x)
	tp := getNat(2 * n)
	t := *tp // temporary variable to hold the products