The representation of a function f(x), which is periodic in x, as an infinite series of sine and cosine functions,
a0 = ∫π-π f(x)dx, an = ∫π-πf(x) cosnxdx, (n = 1,2,3,…), bn = 1/π ∫π-π f(x) sinxdx, (n = 1,2,3,…).
Fourier analysis and Fourier series are named after the French mathematician and engineer Joseph Fourier (1768–1830). Fourier series have many important applications in mathematics, science, and engineering, having been invented by Fourier in the first quarter of the 19th century in his analysis of the problem of heat conduction- dihedral
- dilatancy
- dilation
- dilatometer
- dimensional analysis
- dimensions
- diode
- dioptre
- dip
- dipole
- dipole radiation
- dipole-dipole interaction
- Dirac constant
- Dirac equation
- Dirac, Paul Adrien Maurice
- direct current
- direct motion
- direct-current motor
- directrix
- discharge
- discontinuous function
- disintegration
- disintegration constant
- diskette
- dislocation