 The space of test functions employed here, the so-called Schwartz space "S"(R"n"), is the function space of all infinitely differentiable functions that are rapidly decreasing at infinity along with all partial derivatives.Thus is in the Schwartz space provided that any derivative of "formula_1", multiplied with any power of |"x"|, converges towards 0 for |"x"| → ∞.These functions form a complete topological vector space with a suitably defined family of seminorms.