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  2. 68–95–99.7 rule - Wikipedia

    en.wikipedia.org/wiki/68–95–99.7_rule

    In the empirical sciences, the so-called three-sigma rule of thumb (or 3 σ rule) expresses a conventional heuristic that nearly all values are taken to lie within three standard deviations of the mean, and thus it is empirically useful to treat 99.7% probability as near certainty.

  3. List of trigonometric identities - Wikipedia

    en.wikipedia.org/wiki/List_of_trigonometric...

    Visual demonstration of the double-angle formula for sine. For the above isosceles triangle with unit sides and angle 2 θ {\displaystyle 2\theta } , the area ⁠ 1 / 2 ⁠ × base × height is calculated in two orientations.

  4. Summation - Wikipedia

    en.wikipedia.org/wiki/Summation

    In mathematics, summation is the addition of a sequence of numbers, called addends or summands; the result is their sum or total.Beside numbers, other types of values can be summed as well: functions, vectors, matrices, polynomials and, in general, elements of any type of mathematical objects on which an operation denoted "+" is defined.

  5. Sigmoid function - Wikipedia

    en.wikipedia.org/wiki/Sigmoid_function

    Inverted logistic S-curve to model the relation between wheat yield and soil salinity. Many natural processes, such as those of complex system learning curves, exhibit a progression from small beginnings that accelerates and approaches a climax over time.

  6. Symbolab - Wikipedia

    en.wikipedia.org/wiki/Symbolab

    Symbolab is an answer engine [1] that provides step-by-step solutions to mathematical problems in a range of subjects. [2] It was originally developed by Israeli start-up company EqsQuest Ltd., under whom it was released for public use in 2011.

  7. Log-normal distribution - Wikipedia

    en.wikipedia.org/wiki/Log-normal_distribution

    The way it is done there is that we have two approximately Normal distributions (e.g., p1 and p2, for RR), and we wish to calculate their ratio. [b] However, the ratio of the expectations (means) of the two samples might also be of interest, while requiring more work to develop. The ratio of their means is:

  8. Box–Muller transform - Wikipedia

    en.wikipedia.org/wiki/Box–Muller_transform

    #include <cmath> #include <limits> #include <random> #include <utility> //"mu" is the mean of the distribution, and "sigma" is the standard deviation. std:: pair < double, double > generateGaussianNoise (double mu, double sigma) {constexpr double two_pi = 2.0 * M_PI; //initialize the random uniform number generator (runif) in a range 0 to 1 ...

  9. Error function - Wikipedia

    en.wikipedia.org/wiki/Error_function

    (), where (2n − 1)!! is the double factorial of (2n − 1), which is the product of all odd numbers up to (2n − 1). This series diverges for every finite x , and its meaning as asymptotic expansion is that for any integer N ≥ 1 one has erfc ⁡ x = e − x 2 x π ∑ n = 0 N − 1 ( − 1 ) n ( 2 n − 1 ) ! !