A request that this article title be changed to One-half is under discussion . Please do not move this article until the discussion is closed. |
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Cardinal | one half | |||
Ordinal | 1⁄2th (halfth) | |||
Binary | 0.12 | |||
Ternary | 0.11111111113 | |||
Senary | 0.36 | |||
Octal | 0.48 | |||
Duodecimal | 0.612 | |||
Hexadecimal | 0.816 | |||
Greek | ∠ | |||
Roman numerals | S | |||
Egyptian hieroglyph | 𓐛 | |||
Hebrew | חֵצִ | |||
Malayalam | ൴ | |||
Chinese | 半 | |||
Tibetan | ༪ |
One half is the irreducible fraction resulting from dividing one (1) by two (2), or the fraction resulting from dividing any number by its double.
It often appears in mathematical equations, recipes, measurements, etc.
One half is one of the few fractions which are commonly expressed in natural languages by suppletion rather than regular derivation. In English, for example, compare the compound "one half" with other regular formations like "one-sixth".
A half can also be said to be one part of something divided into two equal parts. It is acceptable to write one half as a hyphenated word, one-half.
One half is a rational number that lies midway between nil and unity (which are the elementary additive and multiplicative identities) as the quotient of the first two non-zero integers, . It has two different decimal representations in base ten, the familiar and the recurring , with a similar pair of expansions in any even base; while in odd bases, one half has no terminating representation, it has only a single representation with a repeating fractional component (such as in ternary and in quinary).
Multiplication by one half is equivalent to division by two, or "halving"; conversely, division by one half is equivalent to multiplication by two, or "doubling".
A number raised to the power of one half is equal to the square root of ,
A hemiperfect number is a positive integer with a half-integer abundancy index:
where is odd, and is the sum-of-divisors function. The first three hemiperfect numbers are 2, 24, and 4320. [1]
The area of a triangle with base and altitude is computed as
One half figures in the formula for calculating figurate numbers, such as the -th triangular number:
and in the formula for computing magic constants for magic squares,
Successive natural numbers yield the -th metallic mean by the equation,
In the study of finite groups, alternating groups have order
By Euler, a classical formula involving pi, and yielding a simple expression: [4]
where is the number of prime factors of the form of (see modular arithmetic).
For the gamma function, a non-integer argument of one half yields,
while inside Apéry's constant, which represents the sum of the reciprocals of all positive cubes, there is [5] [6]
with the polygamma function of order on the complex numbers .
The upper half-plane is the set of points in the Cartesian plane with . In the context of complex numbers, the upper half-plane is defined as
In differential geometry, this is the universal covering space of surfaces with constant negative Gaussian curvature, by the uniformization theorem.
The Bernoulli number has the value (its sign depending on competing conventions).
The Riemann hypothesis is the conjecture that every nontrivial complex root of the Riemann zeta function has a real part equal to .
½ | |
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vulgar fraction one half | |
In Unicode | U+00BD½VULGAR FRACTION ONE HALF |
Related | |
See also | U+00BC¼ VULGAR FRACTION ONE QUARTER U+00BE¾ VULGAR FRACTION THREE QUARTERS |
The "one-half" symbol has its own code point as a precomposed character in the Number Forms block of Unicode, rendering as ½. [7]
The reduced size of this symbol may make it illegible to readers with relatively mild visual impairment; consequently the decomposed forms 1⁄2 or 1/2 may be more appropriate.
In mathematics, the gamma function is one commonly used extension of the factorial function to complex numbers. The gamma function is defined for all complex numbers except the non-positive integers. For every positive integer n,
The Riemann zeta function or Euler–Riemann zeta function, denoted by the Greek letter ζ (zeta), is a mathematical function of a complex variable defined as
In a distribution, full width at half maximum (FWHM) is the difference between the two values of the independent variable at which the dependent variable is equal to half of its maximum value. In other words, it is the width of a spectrum curve measured between those points on the y-axis which are half the maximum amplitude. Half width at half maximum (HWHM) is half of the FWHM if the function is symmetric. The term full duration at half maximum (FDHM) is preferred when the independent variable is time.
The imaginary unit or unit imaginary number is a solution to the quadratic equation x2 + 1 = 0. Although there is no real number with this property, i can be used to extend the real numbers to what are called complex numbers, using addition and multiplication. A simple example of the use of i in a complex number is 2 + 3i.
In number theory, Euler's totient function counts the positive integers up to a given integer n that are relatively prime to n. It is written using the Greek letter phi as or , and may also be called Euler's phi function. In other words, it is the number of integers k in the range 1 ≤ k ≤ n for which the greatest common divisor gcd(n, k) is equal to 1. The integers k of this form are sometimes referred to as totatives of n.
In mathematics, the harmonic series is the infinite series formed by summing all positive unit fractions:
Euler's constant is a mathematical constant, usually denoted by the lowercase Greek letter gamma, defined as the limiting difference between the harmonic series and the natural logarithm, denoted here by log:
In mathematics, Stirling's approximation is an asymptotic approximation for factorials. It is a good approximation, leading to accurate results even for small values of . It is named after James Stirling, though a related but less precise result was first stated by Abraham de Moivre.
In mathematics, the n-th harmonic number is the sum of the reciprocals of the first n natural numbers:
In vector calculus, Green's theorem relates a line integral around a simple closed curve C to a double integral over the plane region D bounded by C. It is the two-dimensional special case of Stokes' theorem.
In mathematics, theta functions are special functions of several complex variables. They show up in many topics, including Abelian varieties, moduli spaces, quadratic forms, and solitons. As Grassmann algebras, they appear in quantum field theory.
In mathematics, Felix Klein's j-invariant or j function, regarded as a function of a complex variable τ, is a modular function of weight zero for SL(2, Z) defined on the upper half-plane of complex numbers. It is the unique such function which is holomorphic away from a simple pole at the cusp such that
In mathematics, a confluent hypergeometric function is a solution of a confluent hypergeometric equation, which is a degenerate form of a hypergeometric differential equation where two of the three regular singularities merge into an irregular singularity. The term confluent refers to the merging of singular points of families of differential equations; confluere is Latin for "to flow together". There are several common standard forms of confluent hypergeometric functions:
In probability theory and statistics, the chi distribution is a continuous probability distribution over the non-negative real line. It is the distribution of the positive square root of a sum of squared independent Gaussian random variables. Equivalently, it is the distribution of the Euclidean distance between a multivariate Gaussian random variable and the origin. It is thus related to the chi-squared distribution by describing the distribution of the positive square roots of a variable obeying a chi-squared distribution.
In mathematics, Apéry's constant is the sum of the reciprocals of the positive cubes. That is, it is defined as the number
In mathematics, the Riemann zeta function is a function in complex analysis, which is also important in number theory. It is often denoted and is named after the mathematician Bernhard Riemann. When the argument is a real number greater than one, the zeta function satisfies the equation
A yield surface is a five-dimensional surface in the six-dimensional space of stresses. The yield surface is usually convex and the state of stress of inside the yield surface is elastic. When the stress state lies on the surface the material is said to have reached its yield point and the material is said to have become plastic. Further deformation of the material causes the stress state to remain on the yield surface, even though the shape and size of the surface may change as the plastic deformation evolves. This is because stress states that lie outside the yield surface are non-permissible in rate-independent plasticity, though not in some models of viscoplasticity.
A hydrogen-like atom (or hydrogenic atom) is any atom or ion with a single valence electron. These atoms are isoelectronic with hydrogen. Examples of hydrogen-like atoms include, but are not limited to, hydrogen itself, all alkali metals such as Rb and Cs, singly ionized alkaline earth metals such as Ca+ and Sr+ and other ions such as He+, Li2+, and Be3+ and isotopes of any of the above. A hydrogen-like atom includes a positively charged core consisting of the atomic nucleus and any core electrons as well as a single valence electron. Because helium is common in the universe, the spectroscopy of singly ionized helium is important in EUV astronomy, for example, of DO white dwarf stars.
In mathematics, the Struve functionsHα(x), are solutions y(x) of the non-homogeneous Bessel's differential equation:
In geometry, a ball is a region in a space comprising all points within a fixed distance, called the radius, from a given point; that is, it is the region enclosed by a sphere or hypersphere. An n-ball is a ball in an n-dimensional Euclidean space. The volume of a n-ball is the Lebesgue measure of this ball, which generalizes to any dimension the usual volume of a ball in 3-dimensional space. The volume of a n-ball of radius R is where is the volume of the unit n-ball, the n-ball of radius 1.