envelope equation
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Envelope (mathematics) — In mathematics, an envelope of a family of manifolds (especially a family of curves) is a manifold that is tangent to each member of the family at some point.Envelope of a family of curvesThe simplest formal expression for an envelope of curves… … Wikipedia
Envelope detector — An envelope detector is an electronic circuit that takes a high frequency signal as input, and provides an output which is the envelope of the original signal. The capacitor in the circuit stores up charge on the rising edge, and releases it… … Wikipedia
First order partial differential equation — In mathematics, a first order partial differential equation is a partial differential equation that involves only first derivatives of the unknown function of n variables. The equation takes the form: F(x 1,ldots,x n,u,u {x 1},ldots u {x n}) =0 … Wikipedia
Nonlinear Schrödinger equation — This page is about the equation iψt = −½ψxx + κ|ψ|2ψ. For the equation iψt = −½ψxx + V(x)ψ + κ|ψ|2ψ, used in Bose–Einstein condensate theory, see Gross–Pitaevskii equation. In theoretical physics, the nonlinear Schrödinger equation (NLS) is a… … Wikipedia
Slowly varying envelope approximation — In physics, the slowly varying envelope approximation (SVEA) is the assumption that the envelope of a forward travelling wave pulse varies slowly in time and space compared to a period or wavelength. This requires the spectrum of the signal to be … Wikipedia
Bellman equation — A Bellman equation (also known as a dynamic programming equation), named after its discoverer, Richard Bellman, is a necessary condition for optimality associated with the mathematical optimization method known as dynamic programming. It writes… … Wikipedia
Clairaut's equation — In mathematics, a Clairaut s equation is a differential equation of the form To solve such an equation, we differentiate with respect to x, yielding so Hence, either … Wikipedia
Karoubi envelope — In mathematics the Karoubi envelope (or Cauchy completion, but that term has other meanings) of a category C is a classification of the idempotents of C, by means of an auxiliary category. It is named for the French mathematician Max… … Wikipedia
Ultrashort pulse — In optics, an ultrashort pulse of light is an electromagnetic pulse whose time duration is on the order of the femtosecond (10 − 15 second). Such pulses have a broadband optical spectrum, and can be created by mode locked oscillators. They are… … Wikipedia
Dispersion (optics) — This article is about dispersion of waves in optics. For other forms of dispersion, see Dispersion (disambiguation). In a prism, material dispersion (a wavelength dependent refractive index) causes different colors to refract at different angles … Wikipedia
Subwavelength-diameter optical fibre — A subwavelength diameter fibre wraps light around human hair. Subwavelength diameter optical fibre (SDF or SDOF) is an optical fibre whose diameter is less than the wavelength of the light being propagated through the fibre. An SDOF usually… … Wikipedia
