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  2. Homoscedasticity and heteroscedasticity - Wikipedia

    en.wikipedia.org/wiki/Homoscedasticity_and...

    A classic example of heteroscedasticity is that of income versus expenditure on meals. A wealthy person may eat inexpensive food sometimes and expensive food at other times. A poor person will almost always eat inexpensive food. Therefore, people with higher incomes exhibit greater variability in expenditures on food.

  3. Linear discriminant analysis - Wikipedia

    en.wikipedia.org/wiki/Linear_discriminant_analysis

    Linear discriminant analysis (LDA), normal discriminant analysis (NDA), canonical variates analysis (CVA), or discriminant function analysis is a generalization of Fisher's linear discriminant, a method used in statistics and other fields, to find a linear combination of features that characterizes or separates two or more classes of objects or ...

  4. Discriminant - Wikipedia

    en.wikipedia.org/wiki/Discriminant

    For small degrees, the discriminant is rather simple (see below), but for higher degrees, it may become unwieldy. For example, the discriminant of a general quartic has 16 terms, [3] that of a quintic has 59 terms, [4] and that of a sextic has 246 terms. [5] This is OEIS sequence A007878.

  5. Quartic equation - Wikipedia

    en.wikipedia.org/wiki/Quartic_equation

    Single Multiplicity-2 (SM2): when the general quartic equation can be expressed as () () =, where , , and are three different real numbers or is a real number and and are a couple of non-real complex conjugate numbers. This case is divided into two subcases, those that can be reduced to a biquadratic equation and those in which this is impossible.

  6. Quadratic equation - Wikipedia

    en.wikipedia.org/wiki/Quadratic_equation

    If a, b, and c are real numbers and the domain of f is the set of real numbers, then the roots of f are exactly the x-coordinates of the points where the graph touches the x-axis. If the discriminant is positive, the graph touches the x-axis at two points; if zero, the graph touches at one point; and if negative, the graph does not touch the x ...

  7. Iris flower data set - Wikipedia

    en.wikipedia.org/wiki/Iris_flower_data_set

    Scatterplot of the data set. The Iris flower data set or Fisher's Iris data set is a multivariate data set used and made famous by the British statistician and biologist Ronald Fisher in his 1936 paper The use of multiple measurements in taxonomic problems as an example of linear discriminant analysis. [1]

  8. Cubic equation - Wikipedia

    en.wikipedia.org/wiki/Cubic_equation

    If the three roots are real and distinct, the discriminant is a product of positive reals, that is > If only one root, say r 1, is real, then r 2 and r 3 are complex conjugates, which implies that r 2 – r 3 is a purely imaginary number, and thus that (r 2 – r 3) 2 is real and negative.

  9. Logarithmic spiral - Wikipedia

    en.wikipedia.org/wiki/Logarithmic_spiral

    Complex exponential function: The exponential function exactly maps all lines not parallel with the real or imaginary axis in the complex plane, to all logarithmic spirals in the complex plane with centre at : () = (+) + ⏟ = + = (⁡ + ⁡) ⏟ The pitch angle of the logarithmic spiral is the angle between the line and the imaginary axis.