All articles starting with L

Linear combination

A linear combination is an expression of the form c1v1 + ... + ckvk, formed by scaling vectors and adding them; it underlies span, independence, and bases.

Linear combination of atomic orbitals

The linear combination of atomic orbitals (LCAO) is a quantum chemistry method that expresses each molecular orbital as a weighted sum of atomic orbital basis functions.

Linear combination of unitaries

The linear combination of unitaries (LCU) is a quantum-computing technique that implements non-unitary operations as weighted sums of unitaries, introduced for Hamiltonian simulation by Childs and Wiebe in 2012.

Linear complementarity problem contact formulation

The linear complementarity problem contact formulation writes rigid-body contact dynamics with Coulomb friction as an LCP; the Anitescu-Potra version of 1997 was the first proved solvable for any contact configuration.

Linear compressor

A linear compressor is a gas compressor in which a linear electric motor drives the piston directly, without a crank mechanism, first commercialized by LG in 2001.

Linear congruential generator

A linear congruential generator (LCG) is a pseudorandom number generator defined by the recurrence X(n+1) = (aXn + c) mod m, proposed by Lehmer in 1951.

Linear cryptanalysis

Linear cryptanalysis is a known-plaintext attack that recovers bits of a cipher's key from linear approximations; Matsui used it to break full DES in 1994.

Linear dichroism

Linear dichroism is the difference in a sample's absorption of light linearly polarized in two perpendicular directions, used to study molecular orientation in DNA, proteins, liquid crystals, and solids.

Linear differential equation

A linear differential equation is a differential equation in which the unknown and its derivatives appear only to the first power, never multiplied together or inside nonlinear functions.

Sep 19, 2026

Linear Elamite

Linear Elamite is a Bronze Age writing system used in southern Iran from about 2900 to 1900 BCE, best known from the Susa inscriptions of Puzur-Inšušinak.

Linear elasticity

Linear elasticity is the branch of continuum mechanics describing how solids deform under small loads, with stress proportional to strain via Hooke's law and governed by the Navier-Cauchy equations.

Linear energy transfer

Linear energy transfer (LET) is a measure of the energy a charged particle transfers locally to matter per unit track length, central to radiobiology and radiation therapy.

Linear equation

A linear equation, also called a first-degree equation, is an algebraic equation where each variable appears only to the first power, as in ax + b = 0.

Linear filter

A linear filter transforms a signal or image by convolution with a small array of weights called a kernel, to smooth, sharpen, denoise, detect edges, or undo blur.

Linear focal elastosis

Linear focal elastosis (elastotic striae) is a rare benign acquired dermal elastosis with palpable yellow horizontal striae-like bands on the lower back, first described by Burket in 1989, male-predominant (5:1), requiring no treatment.

Linear Fresnel reflector

A linear Fresnel reflector (LFR) is a concentrating solar power collector in which long, parallel mirror strips reflect sunlight onto a fixed elevated receiver, trading optical efficiency for lower cost.

Linear friction welding

Linear friction welding is a solid-state joining process that rubs two workpieces together under compressive force, generating frictional heat that bonds them without melting; it is used mainly for aircraft engine blisks.

Linear function

A linear function, also called a linear map or linear transformation, is a function between vector spaces that preserves vector addition and scalar multiplication; it is represented by a matrix.

Linear generator

A linear generator is an electrical machine converting reciprocating straight-line motion directly into electricity, without a crankshaft or gearbox, mainly in wave energy converters and free-piston engine generators.

Linear gingival erythema

Linear gingival erythema (LGE), formerly HIV-gingivitis, is a fiery red 2-3 mm band along the free gingival margin in immunosuppressed people, mainly HIV, linked to Candida and unresponsive to plaque removal.

Linear IgA dermatosis

Linear IgA dermatosis (linear IgA bullous dermatosis, chronic bullous disease of childhood) is a rare autoimmune subepidermal blistering disease with linear IgA at the basement membrane zone, treated first with dapsone.

Linear independence

Linear independence is the property of a set of vectors where no vector is a linear combination of the others; it is half of the definition of a basis.

Linear induction motor

A linear induction motor is an electric machine producing thrust directly along a straight path, like a rotary induction motor unrolled flat, used in urban metros and low-speed maglev.

Linear interpolation

Linear interpolation is a method of estimating a function's value between two known data points by following the straight line joining them, the simplest and most widely used interpolation method.

Linear inverted pendulum model

The linear inverted pendulum model is a simplified model for humanoid bipedal walking, introduced by Shuuji Kajita and Kazuo Tani in 1991 and extended to three dimensions in 2001.

Linear least squares

Linear least squares is a method of fitting a linear model to data by minimizing the sum of squared deviations between observations and predictions, first published by Legendre in 1805.

Linear lichen planus

Linear lichen planus, or Blaschkoid LP, is a rare lichen planus variant with pruritic violaceous papules along Blaschko lines, distinguished from lichen striatus histologically and treated first with topical corticosteroids.

Linear logic

Linear logic is a substructural logic introduced by Jean-Yves Girard in 1987 that treats formulas as resources, dropping contraction and weakening so each assumption must be used exactly once.

Linear low-density polyethylene

Linear low-density polyethylene (LLDPE) is a semicrystalline polyethylene copolymer in which ethylene is polymerized with an alpha-olefin such as 1-butene, widely used in stretch film and food packaging.