 The result of the block convolution must be added together to produce the complete filter output formula_61.As the support of formula_145 is greater than the support of formula_151, the output blocks will of necessity overlap, but the degree of that overlap is limited.The convolutions of the formula_151 and formula_153 can be evaluated by means of discrete Fourier transforms, provided that the size of the transform is large enough to support formula_145.