An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

Homepage

Number of Results: 76 Search : function
 nested function   کریای ِ تو-در-تو   karyâ-ye tu-dar-tuFr.: fonction imbriquée   In computer programing, a function that is defined inside the definition of another function.→ nested; → function. non-algebraic function   کریای ِ ناجبری   karyâ-ye nâjabriFr.: fonction non algébrique   A → transcendental function. Examples are: exponential, logarithmic, and trigonometric functions.→ non-; → algebraic + → function. optical transfer function (OTF)   کریا‌یِ تراوژ ِ نوری   karyâ-ye tarâvaž-e nuriFr.: fonction de transfert optique   The function that provides a full description of the imaging quality of an optical system. A combination of the → modulation transfer function (MTF) and the → phase transfer function (PTF) , the OTF describes the spatial (angular) variation as a function of spatial (angular) frequency.→ optical; → transfer; → function. orthogonal functions   کریاهایِ ارداکنج   karyâhâ-ye ardâkonjFr.: fonctions orthogonales   A set of functions, any two of which, by analogy to orthogonal vectors, vanish if their product is summed by integration over a specified interval.→ orthogonal; → function. partition function   کرپای ِ پرکش   karâ-ye parkešFr.: fonction de partition   See → integer partition.→ partition; → function. periodic function   کریای ِ دوره‌ای   karyâ-ye dowreyiFr.: fonction périodique   A function f(x) if for all x, f(x + P) = f(x), where P is a positive constant. The least value of P > 0 is called the period of f(x).→ periodic; → function. phase function   کریای ِ فاز   karyâ-ye fâzFr.: fonction de phase   The variation in brightness of a target as the phase angle (the angle between Sun and observer as seen from the target) varies between 0° and 180°. The directional distribution of reflected (or scattered) radiation. The phase angle is the supplement of the scattering angle (the angle between the incident ray and the emerging ray); in other words, the sum of the phase angle and the scattering angle is always 180° (Ellis et al., 2007, Planetary Ring Systems, Springer).→ phase; → function. phase transfer function (PTF)   کریای ِ تراوژ ِ فاز   karyâ-ye tarâvaž-e fâzFr.: fonction de transfert de phase   A measure of the relative phase in the image as function of frequency. It is the phase component of the → optical transfer function. A relative phase change of 180°, for example, results in an image with the black and white areas reversed.→ phase; → transfer; → function. piecewise continuous function   کریای ِ پیوسته‌ی ِ تکه‌ای   karyâ-ye peyvaste-ye tekke-yiFr.: fonction continue par morceaux   A function f(x) in an interval if :1) the interval can be divided into a finite number of pieces in each of which f(x) is continuous, and 2) the limits of f(x) as x approaches the boundary point of each piece are finite. In other words, a piecewise continuous function is one that is made up of a finite number of continuous pieces.→ piecewise; → continuous; → function. Planck function   کریای ِ پلانک   karyâ-ye PlanckFr.: fonction de Planck   Same as → Planck's blackbody formula.→ Planck; → function. point spread function (PSF)   کریای ِ گسترش ِ نقطه، ~ ~ پنده   karyâ-ye gostareš-e noqté, ~ ~ pandéFr.: fonction d'étalement du point   The two-dimensional intensity distribution about the image of a point source.→ point; → spread; → function. power function   کریای ِ توانی   karyâ-ye tavâniFr.: fonction de puissance   A function of the form f(x) = xn, where n is a → real number.→ power; → function. present-day mass function (PDMF)   کریای ِ جرم ِ کنونی، ~ ~ امروزی   karyâ-ye jerm-e konuni, ~ ~ emruziFr.: fonction de masse actuelle   The present number of stars on the → main sequence per unit logarithmic mass interval per square parsec. The PDMF is the basis for deriving the → initial mass function (IMF). This mass function is not corrected for stellar evolution nor losses through stellar deaths.→ present; → day; → mass; → function. probability density function   کریای ِ چگالی ِ شوانایی   karyâ-ye cagâli-ye šavânâyiFr.: fonction de densité de probabilité   A mathematical function whose integral over any interval gives the probability that a continuous → random variable has values in this interval. Also known as → density function, frequency function, → probability function.→ probability; → density; → function. probability function   کریای ِ شوانایی   karyâ-ye šavânâyiFr.: fonction de probabilité   A function that represents a probability distribution in terms of integrals. Also called probability density function or density function.→ probability; → function. reddening function   کریای ِ سرخش   karyâ-ye sorxešFr.: fonction de rougissement   The normalized interstellar extinction at a given wavelength. It is defined by f(λ) = A(λ)/A(Hβ) - 1, where A(λ) is the extinction at the given wavelength and A(Hβ) the extinction at Hβ, with f(Hβ) = 0. It is used to → de-redden observed fluxes: I(λ)/I(Hβ) = F(λ)/F(Hβ).10c(Hβ).f(λ), where I represents the flux in the absence of extinction and F the observed flux affected by extinction, c(Hβ) being the → reddening coefficient.→ reddening; → function. regression function   کریای ِ وایازش   karyâ-ye vâyâzešFr.: fonction de régression   A mathematical function that describes the relationship between two or more variables in a set of data.→ regression, → function. regular function   کریای ِ باسامان   karyâ-ye bâsâmânFr.: fonction régulière   A function of a complex variable which is single-valued in a domain and which has a finite derivative at every point.→ regular; → function. Salpeter function   کریای ِ سلپیتر   karyâ-ye SalpeterFr.: équation de Salpeter   The first mathematical description of the → initial mass function (IMF) of newly formed stars of solar to → intermediate-masses. It is proportional to M -2.35, where M is the stellar mass. → Salpeter slope.Named after the Austrian-Australian-American astrophysicist Edwin Ernest Salpeter (1924-2008); → function. Schechter function   کریای ِ ششتر   karyâ-ye SchechterFr.: fonction de Schechter   A mathematical expression that describes the → luminosity function of galaxies. The function correctly reflects the facts that the luminosity function decreases with increasing luminosity and that the decrease is particularly marked at high luminosities. It is expressed as: φ(L) = φ*(L/L*)α exp (-L/L*), which has two parts and three parameters: φ* is an empirically determined amplitude, α is an empirically derived exponent, and L* is a characteristic luminosity which separates the low and high luminosity parts. For small luminosities (L much smaller than L*) the Schechter function approaches a power law, while at high luminosities (L much larger than L*) the frequency of galaxies drops exponentially. φ*, L*, and the faint-end slope α depend on the observed wavelength range, on the → redshift, and on the environment where the galaxies are observed.Named after the American astronomer Paul Schechter (1948-), who proposed the function in 1976 (ApJ 203, 297); → function.