 Given any open subset "V" of "U" containing the support of "T", there is a family of Radon measures in "U", formula_356, such that 
and for very formula_291, formula_292.By using a larger space of test functions "S"(R"n"), 
one can define the space of tempered distributions 
S′(R"n"), a subspace of D′(R"n").These distributions are useful if one studies the Fourier transform