Correlation between fff and ggg, 2 piecewise continuous functions absolutely integrable over (−∞,∞)(-\infty, \infty)(−∞,∞): (f⋆g)(t)=∫−∞∞f(λ)g(λ−t) dλ(f⋆g)(t)=\int_{-\infty}^{\infty}f(\lambda)g(\lambda-t)\,\text{d}\lambda(f⋆g)(t)=∫−∞∞f(λ)g(λ−t)dλ Relation with Convolution (f⋆g)(t)=(−f∗g)(t)=(f∗−g)(t)(f⋆g)(t)=(-f*g)(t) = (f * -g)(t)(f⋆g)(t)=(−f∗g)(t)=(f∗−g)(t)