ABSTRACT
Physics is the branch of science investigating the nature and properties of matter and energy. It includes subjects such as astrophysics, electricity and magnetism, general and special theories of relativity, heat, mechanics, optics, signal processing and quantum mechanics, for example. It is the closest subject aligned to mathematics. The first section introduces the fast Fourier transform (fft). In this book, it is used in signal processing and as a chaos detector, but it has far more applications in the real world and is considered by many to be the most powerful tool in the whole of mathematics. The second section, from nonlinear optics, presents a simple example of how a complex iterative map may be used to model the propagation of light waves through nonlinear optical fibers. Next, equations that model the Josephson junction, a superconducting nonlinear threshold oscillator, are described. Finally, the motion of three celestial bodies in three-dimensional space is described using a system of ODEs, which can be solved numerically using Euler's method.
