An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 13 Search : transform
affine transformation
  ترادیس ِ کروَن   
tarâdis-e karvan

Fr.: transformation affine   

Any → transformation preserving → collinearity.

affine; → transformation.

color transformation
  ترادیس ِ رنگ   
tarâdis-e rang

Fr.: transformation de couleur   

Empirical mathematical transformation applied to the observed magnitudes in order to convert them into a standard system, or into a different system.

color; → transformation.

Fourier transform
  ترادیس ِ فوریه   
tarâdis-e Fourier

Fr.: transformée de Fourier   

A powerful mathematical tool which is the generalization of the → Fourier series for the analysis of non-periodic functions. The Fourier transform transforms a function defined on physical space into a function defined on the space of frequencies, whose values quantify the "amount" of each periodic frequency contained in the original function. The inverse Fourier transform then reconstructs the original function from its transformed frequency components. The integral F(α) = ∫ f(u)e-iαudu is called the Fourier transform of F(x) = (1/2π)∫ f(α)eiαxdx, both integrals from -∞ to + ∞.

Fourier analysis; → transform.

Galilean transformation
  ترادیس ِ گالیله‌ای   
tarâdis-e Gâlile-yi (#)

Fr.: transformation galiléenne   

The method of relating a measurement in one → reference frame to another moving with a constant velocity with respect to the first within the → Newtonian mechanics. The Galilean transformation between the coordinate systems (x,y,z,t) and (x',y',z',t') is expressed by the relations: x' = x - vt, y' = y, z' = z. Galilean transformations break down at high velocities and for electromagnetic phenomena and is superseded by the → Lorentz transformations.

Galilean, of or pertaining to Galileo Galilei (1564-1642), Italian physicist and astronomer; → transformation.

gauge transformation
  ترادیس ِ گز   
tarâdis-e gaz (#)

Fr.: transformation de jauge   

A change of the fields of a gauge theory that does not change the value of any measurable quantity.

gauge; → transformation.

Laplace transform
  ترادیس ِ لاپلاس   
tarâdis-e Laplace (#)

Fr.: transformée de Laplace   

An integral transform of a function obtained by multiplying the given function f(t) by e-pt, where p is a new variable, and integrating with respect to t from t = 0 to t = ∞.

Laplace; → transform.

Legendre transformation
  ترادیسش ِ لوژاندر   
tarâdiseš-e Legendre

Fr.: transformation de Legendre   

A mathematical operation that transforms one function into another. Two differentiable functions f and g are said to be Legendre transforms of each other if their first derivatives are inverse functions of each other: df(x)/dx = (dg(x)/dx)-1. The functions f and g are said to be related by a Legendre transformation.

Legendre equation; → transformation.

Lorentz transformation
  ترادیس ِ لورنتز   
tarâdis-e Lorentz

Fr.: transformation de Lorentz   

A set of linear equations that expresses the time and space coordinates of one → reference frame in terms of those of another one when one frame moves at a constant velocity with respect to the other. In general, the Lorentz transformation allows a change of the origin of a coordinate system, a rotation around the origin, a reversal of spatial or temporal direction, and a uniform movement along a spatial axis. If the system S'(x',y',z',t') moves at the velocity v with respect to S(x,y,z,t) in the positive direction of the x-axis, the Lorentz transformations will be: x' = γ(x - vt), y' = y, z' = z, t' = γ [t - (vx/c2)], where c is the → velocity of light and γ = [1 - (v/c)2]-1/2. For the special case of velocities much less than c, the Lorentz transformation reduces to → Galilean transformation.

Lorentz; → transformation.

similarity transformation
  ترادیسش ِ همانندی   
tarâdiseš-e hamânandi

Fr.: transformation de similarité   

1) A transformation that preserves angles and changes all distances in the same ratio.
2) A transformation of the form B = X-1AX relating two → square matrices A and B.

similarity; → transformation.

transform
  ۱) ترادیس؛ ۲) ترادیسیدن   
1) tarâdis (#); 2) tarâdisidan (#)

Fr.: 1) transformée, transformation; 2) transformer   

1) Math.: A mathematical quantity obtained from a given quantity by an algebraic, geometric, or functional transformation.
The transformation itself.
2) To change in form, appearance, or structure; to change in condition, nature, or character; convert.
Physics: To change into another form of energy.
To increase or decrease (the voltage and current characteristics of an alternating-current circuit), as by means of a transformer.
Math.: To change the form of (a figure, expression, etc.) without in general changing the value.

trans- + → form.

transformation
  ترادیسش، ترادیس   
tarâdiseš (#), tarâdis (#)

Fr.: transformation   

1) The act or process of transforming. The state of being transformed.
2) The relationship between description of a physical phenomenon in one → reference frame to another. → Galilean transformation; → Lorentz transformation.
3) Math.: The act, process, or result of transforming or mapping.

Verbal noun of → transform.

transformer
  ترادیسگر، ترادیسنده   
tarâdisgar (#), tarâdisandé (#)

Fr.: transformateur   

A device that converts low voltages to higher voltages, or vice versa. A transformer consists of a primary coil and a secondary coil, both traversed by the same magnetic flux.

transform + → -or.

unitary transformation
  ترادیس ِ یکایی، ~ یکانی   
tarâdis-e yekâyi, ~ yekâni

Fr.: transformation unitaire   

A transformation whose reciprocal is equal to its Hermitian conjugate.

unitary; → transformation.