An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < alg exp mod Sch > >>

Number of Results: 77 Search : function
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.


Fr.: fonction   

A mathematical rule between two sets which assigns to each element of the first exactly one element of the second, as the expression y = axb.

From M.Fr. fonction, from O.Fr. function, from L. functio (gen. functionis) "performance, execution," from functus, p.p. of fungor "to perform, execute."

Karyâ, from Av. kairya- "function;" cf. Mod.Pers. Laki karyâ "done," Awromâni kiriyây, kiria "to be done," from kar- "to do" (Mod.Pers. kar-, kardan "to do, to make;" Mid.Pers. kardan; O.Pers./Av. kar- "to do, make, build;" Av. kərənaoiti "he makes;" cf. Skt. kr- "to do, to make," krnoti "he makes, he does," karoti "he makes, he does," karma "act, deed;" PIE base kwer- "to do, to make") + -ya suffix of verbal adjectives and nouns (e.g. išya- "desirable," jivya- "living, fresh," haiθya- "true," maidya- "middle," dadya- "grain"); cf. Skt. kāryá- "work, duty, performance."

  ۱) کریایی؛ ۲) کریال   
1) karyâyi; 2) karyâl

Fr.: 1) fonctionnel; 2) fonctionnelle   

1) Math.: Of, relating to, or affecting a function.
2) A → function that associates a → real number or → complex number to a function or a → set of functions. A functional can be considered as a function of a set of several infinite and continuous → variables.

function; → -al.

Gaussian function
  کریای ِ گاؤس   
karyâ-ye Gauss

Fr.: fonction de Gauss   

The function e-x2, whose integral in the interval -∞ to +∞ gives the → square root of the → number pi: ∫e-x2dx = √π. It is the function that describes the → normal distribution.

Gaussian; → function.

Gibbs function
  کریای ِ گیبس   
karyâ-ye Gibbs

Fr.: fonction de Gibbs   

Same as → Gibbs free energy.

Named after Josiah Willard Gibbs (1839-1903), an American physicist who played an important part in the foundation of analytical thermodynamics; → function.

Hamiltonian function
  کریای ِ هامیلتون   
karyâ-ye Hâmilton

Fr.: fonction de Hamilton   

A function that describes the motion of a → dynamical system in terms of the → Lagrangian function, → generalized coordinates, → generalized momenta, and time. For a → holonomic system having n degrees of freedom, the Hamiltonian function is of the form: H = Σpiq.i - L(qi,q.i,t) (summed from i = 1 to n), where L is the Lagrangian function. If L does not depend explicitly on time, the system is said to be → conservative and H is the total energy of the system. The Hamiltonian function plays a major role in the study of mechanical systems. Also called → Hamiltonian.

Introduced in 1835 by the Irish mathematician and physicist William Rowan Hamilton (1805-1865); → function.

hyperbolic function
  کریایِ هذلولی   
karyâ-ye hozluli

Fr.: fonction hyperbolique   

Any of the six functions sinh, cosh, tanh, coth, csch, and sech that are related to the → hyperbola in the same way the → trigonometric functions relate to the → circle. Many of the formulae satisfied by the hyperbolic functions are similar to corresponding formulae for the trigonometric functions, except for + and - signs. For example: cosh2x - sinh2x = 1. See also: → hyperbolic cosine, → hyperbolic sine. Hyperbolic functions were first introduced by the Swiss mathematician Johann Heinrich Lambert (1728-1777).

hyperbolic; → function.

identity function
  کریای ِ ایدانی   
karyâ-ye idâni

Fr.: fonction d'identité   

Math.: Any function f for which f(x) = x for all x in the domain of definition.

identity; → function.

implicit function
  کریای ِ درتاهی   
karyâ-ye dartâhi

Fr.: fonction implicite   

A function which contains two or more variables that are not independent of each other. An implicit function of x and y is one of the form f(x,y) = 0, e.g., 4x + y2 - 9 = 0. See also → explicit function.

implicit; → function.

initial mass function (IMF)
  کریا‌ی ِ آغازین ِ جرم   
karyâ-ye âqâzin-e jerm

Fr.: fonction initiale de masse   

A mathematical expression describing the relative number of stars found in different ranges of mass for a cluster of stars at the time of its formation. It is defined as φ(log M) = dN / dlog M ∝ M, where M is the mass of a star and N is the number of stars in a logarithmic mass interval. The value of the slope found by Salpeter (1955) for → low-mass and → intermediate-mass stars in the → solar neighborhood is Γ = 1.35. The IMF can be expressed also in linear mass units: χ(M) = dN / DM ∝ M. Note that χ(M) = (1 / M lm 10) φ(log M), and α = Γ + 1. In this formalism the Salpeter slope is α = 2.35. There is a third way for representing the IMF, in which the exponent is x = -α. The IMF is not a single power law over all masses, from → brown dwarfs to → very massive stars (Kroupa, 2002, Science 295, 82). Different slopes have been found for different mass segments, as follows: α = 1.3 for 0.08 ≤ Msolar < 0.5; α = 2.3 for 0.5 ≤ Msolar < 1; α = 2.3 for 1 ≤ Msolar. The IMF at low masses can be fitted by a → lognormal distribution (See Bastian et al., 2010, ARAA 48, 339 and references therein). See also → canonical IMF.

initial; → mass; → function.

instrumental response function
  کریای ِ پاسخ ِ سازال   
karyâ-ye pâsox-e sâzâl

Fr.: fonction de la réponse instrumentale   

The mathematical form of the way an instrument affects the input signal.

instrumental; → response; → function.

integral function
  کریای ِ دُرُستالی   
karyâ-ye dorostâli

Fr.: fonction intégrale   

A function whose image is a subset of the integers, i.e. that takes only integer values.

integral; → function.

Lagrangian function
  کریای ِ لاگرانژ   
karyâ-ye lâgrânž (#)

Fr.: Lagrangien, fonction de Lagrange   

A physical quantity (denoted L), defined as the difference between the → kinetic energy (T) and the → potential energy (V) of a system: L = T - V. It is a function of → generalized coordinates, → generalized velocities, and time. Same as → Lagrangian, → kinetic potential.

Lagrangian; → function.

likelihood function
  کریای ِ شدواری   
karyâ-ye šodvâri

Fr.: fonction de vraisemblance   

A function that allows one to estimate unknown parameters based on known outcomes. Opposed to → probability, which allows one to predict unknown outcomes based on known parameters. More specifically, a probability refers to the occurrence of future events, while a likelihood refers to past events with known outcomes.

likelihood; → function.

linear function
  کریای ِ خطی   
karyâ-ye xatti

Fr.: fonction linéaire   

A function expressed by a → first degree equation that can be graphically represented in the → Cartesian coordinate plane by a → straight line.

linear; → function.

luminosity function
  کریا‌ی ِ تابندگی   
karyâ-ye tâbandegi

Fr.: fonction de luminosité   

Number → distribution of → stars or galaxies (→ galaxy) with respect to their → absolute magnitudes. The luminosity function shows the → number of stars of a given intrinsic luminosity (or the number of galaxies per integrated magnitude band) in a given → volume of space.

luminosity; → function.

mass function
  کریای ِ جرم   
karyâ-ye jerm

Fr.: fonction de masse   

1) The number of a class of objects as a function of their mass. → initial mass function (IMF); → present-day mass function (PDMF).
2) A numerical relation between the masses of the two components of a → spectroscopic binary that provides information on the relative masses of the two stars when the spectral lines of only one component can be seen. If Mp is the mass of primary (whose spectrum is known), Ms is the mass of secondary, and i the → angle of inclination of the orbit, the mass function is given by: (Ms3. sin3i) / (Mp + Ms)2.

mass; → function.

membership function
  کریای ِ هموندی   
karyâ-ye hamvandi

Fr.: fonction d'adhésion   

One of several functions used in the → fuzzification and → defuzzification steps of a → fuzzy logic system to map the → nonfuzzy input values to → fuzzy linguistic terms and vice versa. A membership function is used to quantify a linguistic term.

membership; → function.

metallicity distribution function (MDF)
  کریای ِ واباژش ِ فلزیگی   
karyâ-ye vâbâžeš-e felezigi

Fr.: fonction de distribution de métallicité   

A plot representing the number of stars (or systems) per metallicity interval, usually expressed in [Fe/H] (abundance of → iron relative to → hydrogen).

metallicity; → distribution; → function.

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