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  2. Log-normal distribution - Wikipedia

    en.wikipedia.org/wiki/Log-normal_distribution

    Thus, if the random variable X is log-normally distributed, then Y = ln(X) has a normal distribution. [2] [3] Equivalently, if Y has a normal distribution, then the exponential function of Y, X = exp(Y), has a log-normal distribution. A random variable which is log-normally distributed takes only positive real values.

  3. Benford's law - Wikipedia

    en.wikipedia.org/wiki/Benford's_law

    Loglog graph of the probability that a number starts with the digit(s) n, for a distribution satisfying Benford's law. The points show the exact formula, P(n) = log 10 (1 + 1/n). The graph tends towards the dashed asymptote passing through (1, log 10 e) with slope −1 in loglog scale. The example in yellow shows that the probability of a ...

  4. Standard normal table - Wikipedia

    en.wikipedia.org/wiki/Standard_normal_table

    Standard normal table. In statistics, a standard normal table, also called the unit normal table or Z table, [1] is a mathematical table for the values of Φ, the cumulative distribution function of the normal distribution. It is used to find the probability that a statistic is observed below, above, or between values on the standard normal ...

  5. Gamma function - Wikipedia

    en.wikipedia.org/wiki/Gamma_function

    Calculus, mathematical analysis, statistics, physics. In mathematics, the gamma function (represented by Γ, the capital letter gamma from the Greek alphabet) 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.

  6. Davies equation - Wikipedia

    en.wikipedia.org/wiki/Davies_equation

    Davies equation. The Davies equation is an empirical extension of Debye–Hückel theory which can be used to calculate activity coefficients of electrolyte solutions at relatively high concentrations at 25 °C. The equation, originally published in 1938, [1] was refined by fitting to experimental data. The final form of the equation gives the ...

  7. Logarithmic mean - Wikipedia

    en.wikipedia.org/wiki/Logarithmic_mean

    Logarithmic mean. Three-dimensional plot showing the values of the logarithmic mean. In mathematics, the logarithmic mean is a function of two non-negative numbers which is equal to their difference divided by the logarithm of their quotient. This calculation is applicable in engineering problems involving heat and mass transfer.

  8. Euler's constant - Wikipedia

    en.wikipedia.org/wiki/Euler's_constant

    Euler's constant (sometimes called the Euler–Mascheroni constant) is a mathematical constant, usually denoted by the lowercase Greek letter gamma (γ), defined as the limiting difference between the harmonic series and the natural logarithm, denoted here by log: Here, ⌊·⌋ represents the floor function.

  9. Logarithmic integral function - Wikipedia

    en.wikipedia.org/wiki/Logarithmic_integral_function

    Plot of the logarithmic integral function li(z) in the complex plane from -2-2i to 2+2i with colors created with Mathematica 13.1 function ComplexPlot3D. In mathematics, the logarithmic integral function or integral logarithm li(x) is a special function. It is relevant in problems of physics and has number theoretic significance.