Fourier transformations Differential equations, Partial 4 Differential equations, Linear 3 Harmonic analysis 3 Fourier analysis 2 Functions of several complex variables 2 Locally compact Abelian groups 2 Computer algorithms 1 Data processing 1 Digital techniques 1 Electric filters, Digital 1 Fourier series 1 Harmonic analysis on Euclidean spaces 1 Instructional exposition (textbooks, tutorial papers, etc.) 1 Laplace transformation 1 Mathematical physics 1 Numerical solutions 1 Optical data processing 1 Optical transfer function 1 Signal processing 1 System analysis 1 Time measurements 1 Wavelets (Mathematics) 1