Convolution
Appearance
The convolution of two equal-sized vectors x=(xi) and y = (yi) is simply the scalar product
between x and y reversed.
convolution(x,y) = sum i=1 ... n { xi * yn-i}
The convolution of two functions f and g is defined as:
convolution(f,g) = integral -inf ... +inf { f(u) g(x-u) du }