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Sigmoid curves are also common in statistics as cumulative distribution functions (which go from 0 to 1), such as the integrals of the logistic density, the normal density, and Student's t probability density functions. The logistic sigmoid function is invertible, and its inverse is the logit function.
The standard logistic function is the logistic function with parameters =, =, =, which yields = + = + = / / + /.In practice, due to the nature of the exponential function, it is often sufficient to compute the standard logistic function for over a small range of real numbers, such as a range contained in [−6, +6], as it quickly converges very close to its saturation values of 0 and 1.
The generalized logistic function or curve is an extension of the logistic or sigmoid functions. Originally developed for growth modelling, it allows for more flexible S-shaped curves. The function is sometimes named Richards's curve after F. J. Richards, who proposed the general form for the family of models in 1959.
S curve or S-curve may refer to: S-curve (art), an S-shaped curve which serves a wide variety of compositional purposes; S-curve (math), a characteristic S-shaped curve of a sigmoid function; S-curve corset, an Edwardian corset style; S-Curve Records, a record company label; Reverse curve, or "S" curve, in civil engineering
The Gompertz curve or Gompertz function is a type of mathematical model for a time series, named after Benjamin Gompertz (1779–1865). It is a sigmoid function which describes growth as being slowest at the start and end of a given time period.
The mathematical basis for Bézier curves—the Bernstein polynomials—was established in 1912, but the polynomials were not applied to graphics until some 50 years later when mathematician Paul de Casteljau in 1959 developed de Casteljau's algorithm, a numerically stable method for evaluating the curves, and became the first to apply them to computer-aided design at French automaker Citroën ...
A normal distribution is sometimes informally called a bell curve. [8] However, many other distributions are bell-shaped (such as the Cauchy , Student's t , and logistic distributions). (For other names, see Naming .)
If s 0, s 1 and s 2 are known, the roots may be recovered from them with the inverse Fourier transform consisting of inverting this linear transformation; that is, = (+ +), = (+ +), = (+ +). By Vieta's formulas , s 0 is known to be zero in the case of a depressed cubic, and − b / a for the general cubic.