Logistic function

Gives the S-shaped curve that models growth which starts roughly exponentially and levels off at a maximum value. It is used in population biology, epidemiology, and machine learning to model saturating growth or to map real numbers into the interval between 0 and L.

f(x) = \frac{L}{1 + e^{-k(x-x_0)}}

What the symbols mean

value of the function at x
independent variable, often time
maximum value (supremum) of the curve
logistic growth rate or steepness of the curve
x-value of the midpoint, where the curve reaches L/2
Euler's number, the base of the natural logarithm

About this formula

  • FieldMathematics
  • TopicFunctions and growth models
  • LevelUniversity
  • Also calledlogistic growth model, logistic curve, sigmoid function, S-curve, logistic growth formula
  • SourceWikidata Q1052379

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