mass functionn.
/ˈmas ˌfʌŋ(k)ʃn/, U.S. /ˈmæs ˌfəŋ(k)ʃən/ Mathematics and Astronomy.
1. Chiefly Astronomy. A function involving relationships of mass; spec. (a) a relationship used to determine the masses of the two stars of a spectroscopic binary when only the spectrum of one star (m1) can be observed, namely (m23 sin3i)/(m1 + m2)2, where m1 and m2 are the star masses and i is the inclination of the orbit; (b) an expression describing the number of objects per unit volume in different ranges of mass, for a group of stars, galaxies, etc.
ΚΠ
1927 H. N. Russell et al. Astron. II. xx. 705 The average orbital velocity (K) for the bright component corresponds to a mass function (m23 sin3 i)/(m1 + m2)2 of 0·45 for class B., 0·16 for A..and 0·08 for G.
1961 Observatory 81 230 With the exception of three grouped points the initial mass function turns out to be a smoothly varying function.
1969 Astrophysical Jrnl. 156 1019 Single-line binaries with large mass functions are more common among the eclipsing systems in Batten's catalogue than among the non-eclipsing systems.
1995 Observatory 115 84 The mass function has the large value of 0.33 M☉; that, together with slight anomalies noticed on classification spectrograms, suggests that the companion may be a main-sequence star of about type F0.
1996 Astrophysical Jrnl. 470 201 Pixel lensing can measure the luminosity function as well as the mass function of stars in target galaxies to a distance of a few megaparsecs.
2. Mathematics. In full probability mass function. A function giving the probability that a discrete random variable will take a specific value.
ΘΚΠ
the world > relative properties > number > algebra > [noun] > expression > function
function1758
exponential1784
potential function1828
syzygy1850
permutant1852
Green function1863
theta-function1871
Greenian1876
Gudermannian1876
discriminoid1877
Weierstrassian function1878
gradient1887
beta function1888
distribution function1889
Riemann zeta function1899
Airy integral1903
Poisson bracket1904
Stirling approximation1908
functional1915
metric1921
Fourier transform1923
recursive function1934
utility function1934
Airy function1939
transfer function1948
objective function1949
restriction1949
multifunction1954
restriction mapping1956
scalar function1956
Langevin function1960
mass function1961
1961 Ann. Math. Statistics 32 1214 The same notation..will be used to specify the so-called discrete p.d.f., that is, the mass function of the corresponding distribution.
1974 ASTIN Bull. 8 91 There exist..situations where the n random variables have a common mixed density and mass function.
1986 G. Grimmett & D. Welsh Probability ii. 28 The (probability) mass function pX of X is the function which maps ℝ into [0,1] defined by pX(x) = P({ω ∈ Ω : X(ω) = x}).
1993 Ann. Appl. Probability 3 1242 The empirical rank distribution..is the c.d.f. of an m-dimensional random vector S(0), S(1), …,S(m-1)), whose probability mass function is given by P(S(0) = k, S(1) = i(1),…, S(m-1) = ik(m-1) = N−1, for all k = 1,…, N.
This is a new entry (OED Third Edition, December 2000; most recently modified version published online March 2022).
<
n.1927