namespace CppAD {
	template <class Vector>
	void mat_sum_sq(size_t n, Vector& x , Vector& y , Vector& z)
	{	size_t i, j, k;
		// Very simple computation of y = x * x for speed comparison
		for(i = 0; i < n; i++)
		{	for(j = 0; j < n; j++)
			{	y[i * n + j] = 0.;
				for(k = 0; k < n; k++)
					y[i * n + j] += x[i * n + k] * x[k * n + j];
			}
		}
		z[0] = 0.;
		for(i = 0; i < n; i++)
		{	for(j = 0; j < n; j++)
				z[0] += y[i * n + j];
		}
		return;
	}

}