Fr.: astrolabe linéaire
A version of → planispheric astrolabe in which the → celestial sphere and the various circles of altitude and declination are projected on to a line represented by a staff. The staff is equivalent to the meridian line and contains markings to indicate the centers of these circles and their intersections with the meridian. By attaching three ropes to the appropriate points on the staff to act as radii, the circles and their intersections can be reconstructed. One of the ropes was attached to a plumb line. A scale giving chord lengths in the meridian circle extended the linear astrolabe's range of applications. It was invented by the Iranian mathematician and astronomer Sharafeddin Tusi (c1135-1213), but no early example has survived. Same as → Sharafeddin's staff and Tusi's staff.
Fr.: corrélation linéaire
A measure of how well data points fit a straight line. When all the points fall on the line it is called a perfect correlation. When the points are scattered all over the graph there is no correlation.
Fr.: diamètre linéaire
The real physical diameter, as opposed to angular diameter.
linear differential equation
hamugeš-e degarsâne-yi-ye xatti
Fr.: équation différentielle linéaire
An equation in which the → dependent variable y
and all its differential coefficients occur only
in the first degree. A linear differential equation of → order
order n has the form:
linear electric quadrupole
cahârqotbe-ye barqi-ye xatti
Fr.: quadrupôle électrique linéaire
A system of three charges +q, -2q, and +q, arranged along a line to form an axial quadrupole. The → electric potential V due to a linear quadrupole varies as 1/r3, whereas the → electric intensity E varies as 1/r4.
Fr.: équation linéaire
An equation composed of first degree variables and representing a straight line.
Fr.: fonction linéaire
nâpâydâri-ye xatti (#)
Fr.: instabilité linéaire
An instability that can be described (to first-order accuracy) by linear (or tangent linear) equations.
Fr.: quantité de mouvement linéaire
The product of an object's → mass and → velocity. It is a → vector and points in the same direction as the velocity vector. Linear momentum is distinguished from → angular momentum. When there is no opportunity for confusion, usually the term momentum is used instead of linear momentum.
linear perturbation theory
negare-ye partureš-e xatti
Fr.: théorie de perturbation linéaire
Assumption that the variations in the plasma parameters, due to the presence of waves, are small (to the first order) as compared to the undisturbed parameters. This makes it possible to linearize equations by dropping out second order (and higher) nonlinear terms.
qotbeš-e xatti (#)
Fr.: polarisation linéaire
Of an electromagnetic radiation, a → polarization in which the electric vibrations are confined to one plane along the direction of propagation. Also called → plane polarization. See also → circular polarization.
barnâme-sâzi-ye xatti (#)
Fr.: programmation linéaire
A procedure for finding the maximum or minimum of a → linear function where the → arguments are subject to linear → constraints. For problems involving more than two variables or problems involving a large number of constraints, solution methods used are those that are adaptable to computers. A well-known such → algorithm is the → simplex method.
Fr.: regression linéaire
In statistics, a regression method that establishes a linear relationship between two random variables.
Fr.: taille linéaire
The real, physical size, as opposed to angular size.
Fr.: système linéaire
Physics: A → dynamical system whose evolution is a linear process. If a change in any variable at some initial time produces a change in the same or some other variable at some later time, twice as large a change at the same initial time will produce twice as large a change at the same later time.
Fr.: vitesse linéaire
The rate of change of the position of an object that is traveling along a straight path. In other words, the velocity of an object when its moving direction is not changing. For a given → angular velocity (ω), the linear velocity v of the particle is directly proportional to the distance of the particle from the center of the circular path: v = ω ×r.
The property, condition, or state of being linear.
A process of reduction to linear form by appropriate change of variables or by approximation.
Verbal noun of → linearize.
To make linear; give linear form to.
linearized differential equation
hamugeš-e degarsâneyi-ye xatti
Fr.: équation différentielle linéarisée
A differential equation that has been derived from an original nonlinear equation.