Also found in: Wikipedia.


A letter occurring in certain early forms of Greek and transliterated in English as w.

[Latin, from Greek : di-, two; see di-1 + gamma, gamma (because its shape resembles two gammas); see gamma.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Letters of the Alphabet (Foreign)) a letter of the Greek alphabet (Ϝ) that became obsolete before the classical period of the language. It represented a semivowel like English W and was used as a numeral in later stages of written Greek, and passed into the Roman alphabet as F
[C17: via Latin from Greek, from di-1 + gamma; from its shape, which suggests one gamma upon another]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(daɪˈgæm ə)

n., pl. -mas.
a letter of the early Greek alphabet that represented a sound similar to English w and fell into disuse before the classical period.
[1545–55; < Latin < Greek dígamma]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
Mentioned in ?
References in classic literature ?
1) In diction, dialect and style it is obviously dependent upon Homer, and is therefore considerably later than the "Iliad" and "Odyssey": moreover, as we have seen, it is in revolt against the romantic school, already grown decadent, and while the digamma is still living, it is obviously growing weak, and is by no means uniformly effective.
I don't care a straw for Greek particles, or the digamma; no more does his mother.
On the other hand, in [8], we showed that the double cotangent function [Cot.sub.2](x, (1,[tau])) (the logarithmic derivative of the double sine function) degenerates to the digamma function (the logarithmic derivative of the gamma function) as [tau] tends to infinity.
Strumia, "Interpreting the 750 GeV digamma excess: a review," High Energy Physics--Phenomenology, 2016, https:// arxiv.org/abs/1605.09401.
involving the digamma function y that has no singularities and starts with the power n.
The above notion of Schur convexity was first introduced by Schur in 1923 and has many important applications in analytic inequalities [16-20], isoperimetric problem for polytopes [21], linear regression [22], combinatorial optimization [23], graphs and matrices [24], gamma and digamma functions [25], information-theoretic topics [26], stochastic orderings [27], and other related fields.
Notations f(*): Probability density function E(*): Mean function Var(*): Variance function [gamma](y, x): Lower incomplete gamma function [GAMMA](y, x): Upper incomplete gamma function F(*): Cumulative distribution function S(*): Survival function h(*): Hazard rate function L(*): Likelihood function l(*): Log-likelihood function [psi](*): Digamma function [psi]'(*): Trigamma function I(*): Expected Fisher information matrix [mu]: Positive parameter [phi]: Positive parameter [alpha]: Positive parameter [beta]: Real parameter [lambda]: Positive parameter Q(*): Quantile function [THETA]: Vector of parameters H(*: Observed Fisher information matrix [[mu].sub.k]: kth moment G(*: TTT-plot [D.sub.n]: Kolmogorov-Smirnov statistic [y.sup.*]: Predictive value.
[psi](*) is the digamma function and [mathematical expression not reproducible].
where [psi](x) is the digamma function defined as [psi]([theta]) = ([partial derivative]/[partial derivative][theta]) log [GAMMA]([theta]).
ML-based m parameter estimation problem reduces to the problem of solving some transcendental equations written in the form of logarithmic and digamma functions.
where B(a, b) = [GAMMA](a) [GAMMA] (b)/ [GAMMA] (a + b) and [PSI](x)is the digamma function, the asymptotic expression of SOP at high MER can be written as