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48-580: Tammer is the namesake of the Gerstewitz functions or Gerstewitz functionals in vector optimization and its generalizations. Tammer earned a doctorate ( Dr. rer. nat. ) in 1984 at the Technical University Leuna-Merseburg . Her dissertation, Beiträge zur Dualitätstheorie der nichtlinearen Vektoroptimierung , was supervised by Alfred Göpfert  [ de ] . She earned a habilitation at Halle in 1991. Tammer

96-464: A curve can be described as the image of a function whose argument, typically called the parameter , lies in a real interval . For example, the unit circle can be specified in the following two ways: with parameter t ∈ [ 0 , 2 π ) . {\displaystyle t\in [0,2\pi ).} As a parametric equation this can be written The parameter t in this equation would elsewhere in mathematics be called

144-407: A formal parameter and an actual parameter . For example, in the definition of a function such as x is the formal parameter (the parameter ) of the defined function. When the function is evaluated for a given value, as in 3 is the actual parameter (the argument ) for evaluation by the defined function; it is a given value (actual value) that is substituted for the formal parameter of

192-410: A model describes the probability that something will occur. Parameters in a model are the weight of the various probabilities. Tiernan Ray, in an article on GPT-3, described parameters this way: A parameter is a calculation in a neural network that applies a great or lesser weighting to some aspect of the data, to give that aspect greater or lesser prominence in the overall calculation of the data. It

240-457: A functional changes when the input function changes by a small amount. Richard Feynman used functional integrals as the central idea in his sum over the histories formulation of quantum mechanics . This usage implies an integral taken over some function space . Parameter A parameter (from Ancient Greek παρά ( pará )  'beside, subsidiary' and μέτρον ( métron )  'measure'), generally,

288-392: A functional's value can be computed for small segments of the input curve and then summed to find the total value, the functional is called local. Otherwise it is called non-local. For example: F ( y ) = ∫ x 0 x 1 y ( x ) d x {\displaystyle F(y)=\int _{x_{0}}^{x_{1}}y(x)\;\mathrm {d} x}

336-476: A given functional. A particularly important application in physics is search for a state of a system that minimizes (or maximizes) the action , or in other words the time integral of the Lagrangian . The mapping x 0 ↦ f ( x 0 ) {\displaystyle x_{0}\mapsto f(x_{0})} is a function, where x 0 {\displaystyle x_{0}}

384-414: A known point (e.g. "10km NNW of Toronto" or equivalently "8km due North, and then 6km due West, from Toronto" ), which are often simpler for movement confined to a (relatively) small area, like within a particular country or region. Such parametrizations are also relevant to the modelization of geographic areas (i.e. map drawing ). Mathematical functions have one or more arguments that are designated in

432-425: A parameter denotes an element which may be manipulated (composed), separately from the other elements. The term is used particularly for pitch , loudness , duration , and timbre , though theorists or composers have sometimes considered other musical aspects as parameters. The term is particularly used in serial music , where each parameter may follow some specified series. Paul Lansky and George Perle criticized

480-415: A special class of functionals. They map a function f {\displaystyle f} into a real number, provided that H {\displaystyle H} is real-valued. Examples include Given an inner product space X , {\displaystyle X,} and a fixed vector x → ∈ X , {\displaystyle {\vec {x}}\in X,}

528-584: A variable. The quantity x is a dummy variable or variable of integration (confusingly, also sometimes called a parameter of integration ). In statistics and econometrics , the probability framework above still holds, but attention shifts to estimating the parameters of a distribution based on observed data, or testing hypotheses about them. In frequentist estimation parameters are considered "fixed but unknown", whereas in Bayesian estimation they are treated as random variables, and their uncertainty

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576-532: Is a linear function from a vector space to the underlying scalar field, the above linear maps are dual to each other, and in functional analysis both are called linear functionals . Integrals such as f ↦ I [ f ] = ∫ Ω H ( f ( x ) , f ′ ( x ) , … ) μ ( d x ) {\displaystyle f\mapsto I[f]=\int _{\Omega }H(f(x),f'(x),\ldots )\;\mu (\mathrm {d} x)} form

624-434: Is an argument of a function f . {\displaystyle f.} At the same time, the mapping of a function to the value of the function at a point f ↦ f ( x 0 ) {\displaystyle f\mapsto f(x_{0})} is a functional ; here, x 0 {\displaystyle x_{0}} is a parameter . Provided that f {\displaystyle f}

672-625: Is any characteristic that can help in defining or classifying a particular system (meaning an event, project, object, situation, etc.). That is, a parameter is an element of a system that is useful, or critical, when identifying the system, or when evaluating its performance, status, condition, etc. Parameter has more specific meanings within various disciplines, including mathematics , computer programming , engineering , statistics , logic , linguistics , and electronic musical composition. In addition to its technical uses, there are also extended uses, especially in non-scientific contexts, where it

720-456: Is being used. It is not an argument of the function, and will, for instance, be a constant when considering the derivative log b ′ ⁡ ( x ) = ( x ln ⁡ ( b ) ) − 1 {\displaystyle \textstyle \log _{b}'(x)=(x\ln(b))^{-1}} . In some informal situations it is a matter of convention (or historical accident) whether some or all of

768-436: Is computed directly from the data values and thus estimates the parameter known as the population correlation . In probability theory , one may describe the distribution of a random variable as belonging to a family of probability distributions , distinguished from each other by the values of a finite number of parameters . For example, one talks about "a Poisson distribution with mean value λ". The function defining

816-401: Is described as a distribution. In estimation theory of statistics, "statistic" or estimator refers to samples, whereas "parameter" or estimand refers to populations, where the samples are taken from. A statistic is a numerical characteristic of a sample that can be used as an estimate of the corresponding parameter, the numerical characteristic of the population from which the sample

864-430: Is local while F ( y ) = ∫ x 0 x 1 y ( x ) d x ∫ x 0 x 1 ( 1 + [ y ( x ) ] 2 ) d x {\displaystyle F(y)={\frac {\int _{x_{0}}^{x_{1}}y(x)\;\mathrm {d} x}{\int _{x_{0}}^{x_{1}}(1+[y(x)]^{2})\;\mathrm {d} x}}}

912-530: Is non-local. This occurs commonly when integrals occur separately in the numerator and denominator of an equation such as in calculations of center of mass. The traditional usage also applies when one talks about a functional equation, meaning an equation between functionals: an equation F = G {\displaystyle F=G} between functionals can be read as an 'equation to solve', with solutions being themselves functions. In such equations there may be several sets of variable unknowns, like when it

960-483: Is said that an additive map f {\displaystyle f} is one satisfying Cauchy's functional equation : f ( x + y ) = f ( x ) + f ( y )  for all  x , y . {\displaystyle f(x+y)=f(x)+f(y)\qquad {\text{ for all }}x,y.} Functional derivatives are used in Lagrangian mechanics . They are derivatives of functionals; that is, they carry information on how

1008-415: Is the author of books including: She is the co-editor, with Frank Heyde, of Festschrift in celebration of Prof. Dr. Wilfried Grecksch's 60th birthday (Shaker, 2008). Functional (mathematics) In mathematics , a functional is a certain type of function . The exact definition of the term varies depending on the subfield (and sometimes even the author). This article is mainly concerned with

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1056-508: Is these weights that give shape to the data, and give the neural network a learned perspective on the data. In engineering (especially involving data acquisition) the term parameter sometimes loosely refers to an individual measured item. This usage is not consistent, as sometimes the term channel refers to an individual measured item, with parameter referring to the setup information about that channel. "Speaking generally, properties are those physical quantities which directly describe

1104-452: Is used to mean defining characteristics or boundaries, as in the phrases 'test parameters' or 'game play parameters'. When a system is modeled by equations, the values that describe the system are called parameters . For example, in mechanics , the masses, the dimensions and shapes (for solid bodies), the densities and the viscosities (for fluids), appear as parameters in the equations modeling movements. There are often several choices for

1152-401: Is useful to consider all functions with certain parameters as parametric family , i.e. as an indexed family of functions. Examples from probability theory are given further below . W.M. Woods ... a mathematician ... writes ... "... a variable is one of the many things a parameter is not." ... The dependent variable, the speed of the car, depends on the independent variable, the position of

1200-420: Is zero is a vector subspace of X , {\displaystyle X,} called the null space or kernel of the functional, or the orthogonal complement of x → , {\displaystyle {\vec {x}},} denoted { x → } ⊥ . {\displaystyle \{{\vec {x}}\}^{\perp }.} For example, taking

1248-464: The independent variable . In mathematical analysis , integrals dependent on a parameter are often considered. These are of the form In this formula, t is the argument of the function F , and on the right-hand side the parameter on which the integral depends. When evaluating the integral, t is held constant, and so it is considered to be a parameter. If we are interested in the value of F for different values of t , we then consider t to be

1296-468: The parametric statistics just described. For example, a test based on Spearman's rank correlation coefficient would be called non-parametric since the statistic is computed from the rank-order of the data disregarding their actual values (and thus regardless of the distribution they were sampled from), whereas those based on the Pearson product-moment correlation coefficient are parametric tests since it

1344-502: The defined function. (In casual usage the terms parameter and argument might inadvertently be interchanged, and thereby used incorrectly.) These concepts are discussed in a more precise way in functional programming and its foundational disciplines, lambda calculus and combinatory logic . Terminology varies between languages; some computer languages such as C define parameter and argument as given here, while Eiffel uses an alternative convention . In artificial intelligence ,

1392-400: The definition by variables . A function definition can also contain parameters, but unlike variables, parameters are not listed among the arguments that the function takes. When parameters are present, the definition actually defines a whole family of functions, one for every valid set of values of the parameters. For instance, one could define a general quadratic function by declaring Here,

1440-402: The distribution (the probability mass function ) is: This example nicely illustrates the distinction between constants, parameters, and variables. e is Euler's number , a fundamental mathematical constant . The parameter λ is the mean number of observations of some phenomenon in question, a property characteristic of the system. k is a variable, in this case the number of occurrences of

1488-438: The functional is a "function of a function", and some older authors actually define the term "functional" to mean "function of a function". However, the fact that X {\displaystyle X} is a space of functions is not mathematically essential, so this older definition is no longer prevalent. The term originates from the calculus of variations , where one searches for a function that minimizes (or maximizes)

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1536-434: The gas pedal. [Kilpatrick quoting Woods] "Now ... the engineers ... change the lever arms of the linkage ... the speed of the car ... will still depend on the pedal position ... but in a ... different manner . You have changed a parameter" In the context of a mathematical model , such as a probability distribution , the distinction between variables and parameters was described by Bard as follows: In analytic geometry ,

1584-935: The inner product with a fixed function g ∈ L 2 ( [ − π , π ] ) {\displaystyle g\in L^{2}([-\pi ,\pi ])} defines a (linear) functional on the Hilbert space L 2 ( [ − π , π ] ) {\displaystyle L^{2}([-\pi ,\pi ])} of square integrable functions on [ − π , π ] : {\displaystyle [-\pi ,\pi ]:} f ↦ ⟨ f , g ⟩ = ∫ [ − π , π ] f ¯ g {\displaystyle f\mapsto \langle f,g\rangle =\int _{[-\pi ,\pi ]}{\bar {f}}g} If

1632-400: The latter case, it is only defined for non-negative integer arguments. More formal presentations of such situations typically start out with a function of several variables (including all those that might sometimes be called "parameters") such as as the most fundamental object being considered, then defining functions with fewer variables from the main one by means of currying . Sometimes it

1680-536: The map defined by y → ↦ x → ⋅ y → {\displaystyle {\vec {y}}\mapsto {\vec {x}}\cdot {\vec {y}}} is a linear functional on X . {\displaystyle X.} The set of vectors y → {\displaystyle {\vec {y}}} such that x → ⋅ y → {\displaystyle {\vec {x}}\cdot {\vec {y}}}

1728-484: The parameters, and choosing a convenient set of parameters is called parametrization . For example, if one were considering the movement of an object on the surface of a sphere much larger than the object (e.g. the Earth), there are two commonly used parametrizations of its position: angular coordinates (like latitude/longitude), which neatly describe large movements along circles on the sphere, and directional distance from

1776-418: The phenomenon actually observed from a particular sample. If we want to know the probability of observing k 1 occurrences, we plug it into the function to get f ( k 1 ; λ ) {\displaystyle f(k_{1};\lambda )} . Without altering the system, we can take multiple samples, which will have a range of values of k , but the system is always characterized by

1824-406: The physical attributes of the system; parameters are those combinations of the properties which suffice to determine the response of the system. Properties can have all sorts of dimensions, depending upon the system being considered; parameters are dimensionless, or have the dimension of time or its reciprocal." The term can also be used in engineering contexts, however, as it is typically used in

1872-405: The physical sciences. In environmental science and particularly in chemistry and microbiology , a parameter is used to describe a discrete chemical or microbiological entity that can be assigned a value: commonly a concentration, but may also be a logical entity (present or absent), a statistical result such as a 95 percentile value or in some cases a subjective value. Within linguistics,

1920-416: The population from which the sample was drawn. (Note that the sample standard deviation ( S ) is not an unbiased estimate of the population standard deviation ( σ ): see Unbiased estimation of standard deviation .) It is possible to make statistical inferences without assuming a particular parametric family of probability distributions . In that case, one speaks of non-parametric statistics as opposed to

1968-506: The same λ. For instance, suppose we have a radioactive sample that emits, on average, five particles every ten minutes. We take measurements of how many particles the sample emits over ten-minute periods. The measurements exhibit different values of k , and if the sample behaves according to Poisson statistics, then each value of k will come up in a proportion given by the probability mass function above. From measurement to measurement, however, λ remains constant at 5. If we do not alter

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2016-420: The second concept, which arose in the early 18th century as part of the calculus of variations . The first concept, which is more modern and abstract, is discussed in detail in a separate article, under the name linear form . The third concept is detailed in the computer science article on higher-order functions . In the case where the space X {\displaystyle X} is a space of functions,

2064-406: The symbols in a function definition are called parameters. However, changing the status of symbols between parameter and variable changes the function as a mathematical object. For instance, the notation for the falling factorial power defines a polynomial function of n (when k is considered a parameter), but is not a polynomial function of k (when n is considered a parameter). Indeed, in

2112-427: The system, then the parameter λ is unchanged from measurement to measurement; if, on the other hand, we modulate the system by replacing the sample with a more radioactive one, then the parameter λ would increase. Another common distribution is the normal distribution , which has as parameters the mean μ and the variance σ². In these above examples, the distributions of the random variables are completely specified by

2160-486: The type of distribution, i.e. Poisson or normal, and the parameter values, i.e. mean and variance. In such a case, we have a parameterized distribution. It is possible to use the sequence of moments (mean, mean square, ...) or cumulants (mean, variance, ...) as parameters for a probability distribution: see Statistical parameter . In computer programming , two notions of parameter are commonly used, and are referred to as parameters and arguments —or more formally as

2208-448: The variable x designates the function's argument, but a , b , and c are parameters (in this instance, also called coefficients ) that determine which particular quadratic function is being considered. A parameter could be incorporated into the function name to indicate its dependence on the parameter. For instance, one may define the base- b logarithm by the formula where b is a parameter that indicates which logarithmic function

2256-786: The word "parameter" is almost exclusively used to denote a binary switch in a Universal Grammar within a Principles and Parameters framework. In logic , the parameters passed to (or operated on by) an open predicate are called parameters by some authors (e.g., Prawitz , "Natural Deduction"; Paulson , "Designing a theorem prover"). Parameters locally defined within the predicate are called variables . This extra distinction pays off when defining substitution (without this distinction special provision must be made to avoid variable capture). Others (maybe most) just call parameters passed to (or operated on by) an open predicate variables , and when defining substitution have to distinguish between free variables and bound variables . In music theory,

2304-411: Was drawn. For example, the sample mean (estimator), denoted X ¯ {\displaystyle {\overline {X}}} , can be used as an estimate of the mean parameter (estimand), denoted μ , of the population from which the sample was drawn. Similarly, the sample variance (estimator), denoted S , can be used to estimate the variance parameter (estimand), denoted σ , of

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