Wolfram Research
Wolfram Math World: Fourier Transform Exponential Function
This site explains how the Fourier transform of an exponential function is related to the Lorentzian function. Site also contains relevant links.
Interactive Mathematics
Interactive Mathematics: Fast Fourier Transform
The Fast Fourier Transform is applied using examples of digital audio recording. Connections to frequency are made through prisms and the cochlea of the ear.
Paul Dawkins
Paul's Online Notes: Differential Equations
The tutorial explores differential equations. Topics examined are first order differential equations, second order differential equations, Laplace transforms, Fourier series, higher order differential equations, and systems of...
Massachusetts Institute of Technology
Mit: Open Course Ware: Differential Equations
The online course consists of educational materials about differential equation. Video lectures, readings, syllabus, exams, interactive mathlets, and assignments with solutions are included.