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: 75 Search : function
algebraic function
  کریای ِ جبری   
karyâ-ye jabri

Fr.: fonction algébrique   

A function expressed in terms of → polynomials and/or roots of polynomials. In other words, any function y = f(x) which satisfies an equation of the form P0(x)yn + P1(x)yn - 1 + ... + Pn(x) = 0, where P0(x), P1(x), ..., Pn(x) are polynomials in x.

algebraic + → function.

analytic function
  کریای ِ آنالسی   
karyâ-ye ânâlasi

Fr.: fonction analytique   

A function which can be represented by a convergent → power series.

analytic; → function.

autocorrelation function
  کریا‌ی ِ خودهم‌باز‌آنش   
karyâ-ye xod-hambâzâneš

Fr.: fonction d'autocorrélation   

A mathematical function that describes the correlation between two values of the same variable at different points in time.

autocorrelation; → function.

bounded function
  کریای ِ کرانمند، ~ کراندار   
karyâ-ye karânmand, ~ karândâr

Fr.: fonction bornée   

The function y = f(x) in a given range of the argument x if there exists a positive number M such that for all values of x in the range under consideration the inequality | f(x) | ≤ M will be fulfilled. → unbounded function.

bounded; → function.

Brillouin function
  کریای ِ بری‌یویءن   
karyâ-ye Brillouin

Fr.: fonction de Brillouin   

A mathematical function appearing in the → magnetization equation of a → paramagnetic substance.

Brillouin zone; → zone.

cluster mass function (CMF)
  کریای ِ جرم ِ خوشه   
karyâ-ye jerm-e xušé

Fr.: fonction de masse d'amas   

An empirical power-law relation representing the number of clusters as a function of their mass. It is defined as: N(M)dM ∝ MdM, where the exponent α has an estimated value of about 2 and dM is the mass interval. It is believed that this is a universal law applying to a variety of objects including globular clusters, massive young clusters, and H II regions.

cluster; → mass; → function.

collapse of the wave function
  رمبش ِ کریای ِ موج   
rombeš-e karyâ-ye mowj

Fr.: effondrement de la fonction d'onde   

The idea, central to the → Copenhagen Interpretation of quantum theory, whereby at the moment of observation the → wave function changes irreversibly from a description of all of the possibilities that could be observed to a description of only the event that is observed. More specifically, quantum entities such as electrons exist as waves until they are observed, then "collapse" into point-like particles. According to the Copenhagen Interpretation, observation causes the wave function to collapse. However it is not known what causes the wave function to collapse. Same as → wave collapse.

collapse; → wave function.

continuous function
  کریای ِ پیوسته   
karyâ-ye peyvasté

Fr.: fonction continue   

The function y = f(x) is called continuous at the point x = x0 if it is defined in some neighborhood of the point x0 and if lim Δy = 0 when Δx → 0.

continuous; → function.

core mass function (CMF)
  کریای ِ جرم ِ مغزه   
karyâ-ye jerm-e maqzé

Fr.: fonction de masse des cœurs   

The mass distribution of → pre-stellar cores in → star-forming regions. The CMF is usually represented by dN/dM = Mα, where dM is the mass interval, dN the number of cores in that interval, and α takes different values in different mass ranges. In the case of → low-mass stars, it is found that the CMF resembles the → Salpeter function, although deriving the masses and radii of pre-stellar cores is not straightforward. The observational similarity between the CMF and the → initial mass function (IMF) was first put forth by Motte et al. (1988, A&A, 336, 150), and since then many other samples of dense cores have been presented in this context. For example, Nutter & Ward-Thompson (2007, MNRAS 374, 1413), using SCUBA archive data of the Orion star-forming regions, showed that the CMF can be fitted to a three-part → power law consistent with the form of the stellar IMF. Recent results, obtained using observations by the → Herschel Satellite, confirm the similarity between the CMF and IMF with better statistics (Könyves et al. 2010, A&A, 518, L106; André et al. 2010, A&A, 518, L102). Moreover, these works show that the CMF has a → lognormal distribution (i.e. dN/dlog M follows a → Gaussian form against log M), as is the case for the IMF at low masses (below about 1 solar mass).

core; → mass; → function.

cubic function
  کریای ِ کابی   
karyâ-ye kâbi

Fr.: fonction cubique   

A function defined by a → polynomial of → degree three. Its generalized form is: f(x) = ax3 + bx2 + cx + d, where a, b, c and d are constants, and a≠ 0.

cubic; → function.

cumulative distribution function
  کریای ِ واباژش ِ کومشی   
karyâ-ye vâbâžeš-e kumeši

Fr.: fonction de distribution cumulée   

A function that gives the probability that a → random variable X is less than or equal to x, at each possible outcome: F(x) = P(X ≤ x), for -∞ < x < ∞. Same as → distribution function.

cumulative; → distribution; → function.

delta function
  کریای ِ دلتا   
karyâ-ye delta

Fr.: fonction delta   

Same as → Dirac function.

dense core mass function
  کریای ِ جرم ِ مغزه‌ی ِ چگال   
karyâ-ye jerm-e maqze-ye cagâl

Fr.: fonction de masse des cœurs denses   

core mass function.

dense; → core; → mass; → function.

differentiable function
  کریای ِ دگرسانی‌پذیر، ~ دگرسانیدنی   
karyâ-ye degarsânipazir, ~ degarsânidani

Fr.: différentiable   

Property of a mathematical function if it has a → derivative at a given point.

From → differentiable; → function.

Dirac function
  کریای ِ دیراک   
karyâ-ye Dirâk

Fr.: fonction de Dirac   

A function of x defined as being zero for all values of x other than x = x0 and having the definite integral from x = -∞ to x = +∞ equal to unity.

Dirac; → function

distance function
  کریای ِ اپست   
karyâ-ye apest

Fr.: fonction de distance   

Same as → metric.

distance + → function.

distribution function
  کریای ِ واباژش   
karyâ-ye vâbâžeš

Fr.: fonction de distribution   

A function that gives the relative frequency with which the value of a statistical variable may be expected to lie within any specified interval. For example, the Maxwellian distribution of velocities gives the number of particles, in different velocity intervals, in a unit volume.

distribution; → function.

eigenfunction
  ویژکریا   
viž-karyâ

Fr.: fonction propre   

1) Math.: An → eigenvector for a linear → operator on a → vector space whose vectors are → functions. Also known as proper function.
2) Quantum mechanics: A → wave function corresponding to an → eigenvalue. Eigenfunctions represent the stationary → quantum states of a system.

From Ger. Eigenfunktion, from eigen- "characteristic, particular, own" (from P.Gmc. *aigana- "possessed, owned," Du. eigen, O.E. agen "one's own") + → function.

Viž-karyâ, from viž, contraction of vižé "particular, charcteristic" + karyâ, → function. Vižé, from Mid.Pers. apēcak "pure, sacred," from *apa-vēcak "set apart," from prefix apa- + vēcak, from vēxtan (Mod.Pers. bixtan) "to detach, separate, sift, remove," Av. vaēk- "to select, sort out, sift," pr. vaēca-, Skt. vic-, vinakti "to sift, winnow, separate; to inquire."

explicit function
  کریای ِ استاهی   
karyâ-ye ostâhi

Fr.: fonction explicite   

The most usual form of a function in which the dependent variable (written on the left hand side of the Same as → equality sign) is expressed directly in terms of independent variables written on the left (on the right hand side). See also → implicit function.

explicit; → function.

exponential function
  کریای ِ نمایی   
karyâ-ye nemâyi

Fr.: fonction exponentielle   

A function in the form of y = bx defined for every → real number x, with positive base b > 1.

exponential; → function.

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