Mathematics and statistics

Multivariable calculus

Multivariable calculus, also called multivariate calculus, is the branch of calculus extending differentiation and integration to functions of several variables and vector fields, culminating in Green's, Stokes', and Gauss' theorems.

Multivariate adaptive regression splines

Multivariate adaptive regression splines (MARS) is a nonparametric regression method introduced by Jerome H. Friedman in 1991, which fits a response with spline basis functions whose knots are chosen automatically from the data.

Multivariate analysis of variance

Multivariate analysis of variance (MANOVA) is a statistical procedure extending ANOVA to two or more correlated dependent variables, tested simultaneously using statistics such as Wilks' Lambda.

Multivariate empirical mode decomposition

Multivariate empirical mode decomposition (MEMD) is a signal-processing method that decomposes multichannel, non-stationary data into scale-aligned intrinsic mode functions, introduced by Rehman and Mandic in 2009.

Multivariate meta-analysis

Multivariate meta-analysis is a statistical method in evidence synthesis that jointly combines effect estimates for several correlated outcomes from multiple studies, typically giving narrower confidence intervals than separate analyses.

Multivariate normal distribution

The multivariate normal distribution, also called the multivariate Gaussian, generalizes the normal distribution to random vectors of correlated variables, defined by a mean vector and covariance matrix.

Multivariate probit model

The multivariate probit model is a regression model for several correlated binary outcomes, introduced by Ashford and Sowden in 1970 and estimated by simulation or Bayesian methods.

Multivariate stable distribution

A multivariate stable distribution is a probability distribution of a random vector such that every linear combination of its coordinates follows a univariate stable distribution, generalizing the Gaussian and Cauchy laws.

Multivariate statistics

Multivariate statistics is the branch of statistics analyzing several variables measured on the same subjects simultaneously, using tools like principal component analysis, MANOVA, and discriminant analysis.

Multivector

A multivector is an element of a geometric algebra formed as a linear combination of blades of different grades, mixing scalars, vectors, and bivectors in one object.

Murray–von Neumann classification of II₁ factors

The Murray–von Neumann classification of II₁ factors is the program begun by Murray and von Neumann in 1936 and 1943, which introduced the fundamental group invariant of a II₁ factor.

Mutual exclusivity

Mutual exclusivity, also called disjointness, is a property of events in probability theory: mutually exclusive events cannot occur together, so their joint probability is 0 and their probabilities add.

Mutual information

Mutual information, also called transinformation, is an information theory quantity measuring how much knowing one random variable reduces uncertainty about another; it is zero exactly when the variables are independent.

Mutually orthogonal Latin squares

Mutually orthogonal Latin squares (MOLS) are sets of Latin squares in which any two superimposed give every ordered symbol pair exactly once, a combinatorial design concept.

MV-algebra

An MV-algebra, short for many-valued algebra, is an algebraic structure introduced by C. C. Chang in 1958 as the algebraic semantics of Łukasiewicz infinite-valued logic.

Mycielskian

The Mycielskian of a graph G, also called a Mycielski graph, is a construction from 1955 that raises the chromatic number by one while preserving the clique number.

Myriad

A myriad is, precisely, the number ten thousand, the largest number named by one word in ancient Greek; in modern English it loosely means an indefinitely great number.

N-sphere

An n-sphere, also called a hypersphere, is the set of points at a fixed distance from a center in (n + 1)-dimensional space; the 1-sphere is the circle.

Nabla symbol

The nabla symbol, also called del, is an inverted Greek delta used in vector calculus for the differential operator giving the gradient, divergence, curl, and Laplacian.

NACE

NACE, from the French Nomenclature statistique des activités économiques dans la Communauté européenne, is the EU statistical classification of economic activities, in use since 1970.

NAG Library

The NAG Library is a commercial collection of more than 1,600 numerical and statistical algorithms developed by the Numerical Algorithms Group in Oxford, first released in 1971.

Nagumo model

The Nagumo model is a nonlinear reaction-diffusion partial differential equation, named after Jin-Ichi Nagumo, that models nerve impulses along an axon and the spread of genetic traits.

Names for the number 0 in English

English has several names for the number 0: zero, the general term; oh for reading digits; nought in British use; nil for sports scores; and love in tennis.

Names of large numbers

Names of large numbers are the English words for powers of ten beyond a thousand, coined from Latin with the -illion ending, as in million, billion, and trillion.

NAND logic

NAND logic is the construction of Boolean functions and circuits using only the NAND operation, "not both", which can express every other Boolean function, making it a universal gate.

Napier's bones

Napier's bones, also called Napier's rods, are numbered calculating rods described by Scottish mathematician John Napier in 1617, designed to reduce multiplication and division to simple addition.

Narayana number

The Narayana numbers, named for the Canadian mathematician T. V. Narayana, form a symmetric triangular array counting Dyck paths with k peaks; row sums give the Catalan numbers.

Narcissistic number

A narcissistic number, also called an Armstrong number, is a number equal to the sum of its digits each raised to the number of digits, like 153.

Nash equilibrium

The Nash equilibrium is a game theory solution concept formulated by John Nash in 1950, where no player can improve their payoff by changing strategy alone.