Integral operator - Satisfies mathematical properties of integral operator - Product of two after one has been reversed and shifted $$x(t)=x_1(t)\circledast x_2(t)=\int_{-\infty}^\infty x_1(t-\tau)\cdot x_2(\tau)d\tau$$ # Properties 1. $x_1(t)\circledast x_2(t)=x_2(t)\circledast x_1(t)$ 1. Commutativity 2. $(x_1(t)\circledast x_2(t))\circledast x_3(t)=x_1(t)\circledast (x_2(t)\circledast x_3(t))$ 1. Associativity 3. $x_1(t)\circledast [x_2(t)+x_3(t)]=x_1(t)\circledast x_2(t)+ x_1(t)\circledast x_3(t)$ 1. Distributivity 4. $Ax_1(t)\circledast Bx_2(t)=AB[x_1(t)\circledast x_2(t)]$ 1. Associativity with Scalar 5. Symmetrical graph about origin # Applications 1. Communications systems - Shift signal in frequency domain (Frequency modulation) 2. System analysis - Find system output given input and transfer function # Polynomial Multiplication - Convolving coefficients of two poly gives coefficients of product