Fourier transformations Theory of distributions (Functional analysis) 4 Convolutions (Mathematics) 2 Digital techniques 2 Harmonic analysis 2 Signal processing 2 System analysis 2 Analog computers 1 Analytic functions 1 Coherence (Optics) 1 Computer programs 1 Data processing 1 Differential equations, Linear 1 Digital filters (Mathematics) 1 Fourier analysis 1 Fourier series 1 Functionals 1 Functions of complex variables 1 Functions of several complex variables 1 Graphic methods 1 Harmonic functions 1 Locally compact Abelian groups 1 Mathematical physics 1 Nuclear magnetic resonance 1 Number theory 1 Optics 1 Physical optics 1 Pulse techniques (Electronics) 1 Radiofrequency spectroscopy 1 Signal theory (Telecommunication) 1