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  2. Range of a function - Wikipedia

    en.wikipedia.org/wiki/Range_of_a_function

    Sometimes "range" refers to the image and sometimes to the codomain. In mathematics, the range of a function may refer to either of two closely related concepts: the codomain of the function, or; the image of the function. In some cases the codomain and the image of a function are the same set; such a function is called surjective or onto.

  3. Function composition - Wikipedia

    en.wikipedia.org/wiki/Function_composition

    If an airplane's altitude at time t is a(t), and the air pressure at altitude x is p(x), then (p ∘ a)(t) is the pressure around the plane at time t. Function defined on finite sets which change the order of their elements such as permutations can be composed on the same set, this being composition of permutations.

  4. Surjective function - Wikipedia

    en.wikipedia.org/wiki/Surjective_function

    Interpretation for surjective functions in the Cartesian plane, defined by the mapping f : X → Y, where y = f(x), X = domain of function, Y = range of function. Every element in the range is mapped onto from an element in the domain, by the rule f. There may be a number of domain elements which map to the same range element.

  5. Bijection, injection and surjection - Wikipedia

    en.wikipedia.org/wiki/Bijection,_injection_and...

    Bijective composition: the first function need not be surjective and the second function need not be injective. A function is bijective if it is both injective and surjective. A bijective function is also called a bijection or a one-to-one correspondence (not to be confused with one-to-one function, which refers to injection

  6. Essential range - Wikipedia

    en.wikipedia.org/wiki/Essential_range

    Say (,) is equipped with its usual topology. Then the essential range of f is given by . ⁡ = { >: < {: | | <}}. [7]: Definition 4.36 [8] [9]: cf. Exercise 6.11 In other words: The essential range of a complex-valued function is the set of all complex numbers z such that the inverse image of each ε-neighbourhood of z under f has positive measure.

  7. Range (statistics) - Wikipedia

    en.wikipedia.org/wiki/Range_(statistics)

    In descriptive statistics, the range of a set of data is size of the narrowest interval which contains all the data. It is calculated as the difference between the largest and smallest values (also known as the sample maximum and minimum ). [ 1 ]

  8. Compositional data - Wikipedia

    en.wikipedia.org/wiki/Compositional_data

    The vector of D probabilities can be considered as a composition of D parts. As they add to one, one probability can be suppressed and the composition is completely determined. In chemometrics, for the classification of petroleum oils. [4] In a survey, the proportions of people positively answering some different items can be expressed as ...

  9. Euler's totient function - Wikipedia

    en.wikipedia.org/wiki/Euler's_totient_function

    Euler's totient function is a multiplicative function, meaning that if two numbers m and n are relatively prime, then φ(mn) = φ(m)φ(n). [ 4 ] [ 5 ] This function gives the order of the multiplicative group of integers modulo n (the group of units of the ring Z / n Z {\displaystyle \mathbb {Z} /n\mathbb {Z} } ). [ 6 ]