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  2. Codomain - Wikipedia

    en.wikipedia.org/wiki/Codomain

    In mathematics, a codomain or set of destination of a function is a set into which all of the output of the function is constrained to fall. It is the set Y in the notation f: X → Y. The term range is sometimes ambiguously used to refer to either the codomain or the image of a function. A codomain is part of a function f if f is defined as a ...

  3. Covariance and correlation - Wikipedia

    en.wikipedia.org/wiki/Covariance_and_correlation

    correlation. so that. where E is the expected value operator. Notably, correlation is dimensionless while covariance is in units obtained by multiplying the units of the two variables. If Y always takes on the same values as X, we have the covariance of a variable with itself (i.e. ), which is called the variance and is more commonly denoted as ...

  4. Weight function - Wikipedia

    en.wikipedia.org/wiki/Weight_function

    A weight function is a mathematical device used when performing a sum, integral, or average to give some elements more "weight" or influence on the result than other elements in the same set. The result of this application of a weight function is a weighted sum or weighted average. Weight functions occur frequently in statistics and analysis ...

  5. Weak solution - Wikipedia

    en.wikipedia.org/wiki/Weak_solution

    Weak solution. In mathematics, a weak solution (also called a generalized solution) to an ordinary or partial differential equation is a function for which the derivatives may not all exist but which is nonetheless deemed to satisfy the equation in some precisely defined sense. There are many different definitions of weak solution, appropriate ...

  6. Second moment method - Wikipedia

    en.wikipedia.org/wiki/Second_moment_method

    Second moment method. In mathematics, the second moment method is a technique used in probability theory and analysis to show that a random variable has positive probability of being positive. More generally, the "moment method" consists of bounding the probability that a random variable fluctuates far from its mean, by using its moments.

  7. H-infinity methods in control theory - Wikipedia

    en.wikipedia.org/wiki/H-infinity_methods_in...

    The achievable H ∞ norm of the closed loop system is mainly given through the matrix D 11 (when the system P is given in the form (A, B 1, B 2, C 1, C 2, D 11, D 12, D 22, D 21)). There are several ways to come to an H ∞ controller: A Youla-Kucera parametrization of the closed loop often leads to very high-order controller.

  8. Hausdorff moment problem - Wikipedia

    en.wikipedia.org/wiki/Hausdorff_moment_problem

    In the case m 0 = 1, this is equivalent to the existence of a random variable X supported on [0, 1], such that E[X n] = m n. The essential difference between this and other well-known moment problems is that this is on a bounded interval , whereas in the Stieltjes moment problem one considers a half-line [0, ∞) , and in the Hamburger moment ...

  9. Darwin (unit) - Wikipedia

    en.wikipedia.org/wiki/Darwin_(unit)

    Since the difference between two natural logarithms is a dimensionless ratio, the trait may be measured in any unit. Inexplicably, Haldane defined the millidarwin as 10 −9 darwins, despite the fact that the prefix milli- usually denotes a factor of one thousandth (10 −3 ).