Approximate Identity: Functional analysis, Banach algebra, Net (mathematics), Mollifier, Dirac delta function, Fejér kernel, Fourier series, C* Convolution

Fredholm Kernel: Mathematics, Banach Space, Nuclear Operator

Reflection Formula: Function (Mathematics), Functional Equation, Numerical Analysis, Special Function, Complex Plane

Dirac Comb: Mathematics, Electrical engineering, Periodic function, Schwartz distribution, delta Ronald N. Bracewell

Singularity Function: Dirac Delta Function, Heaviside Step Ramp Function