hyperspy._components.logistic module

class hyperspy._components.logistic.Logistic(a=1.0, b=1.0, c=1.0, origin=0.0, module='numexpr', **kwargs)

Bases: Expression

Logistic function (sigmoid or s-shaped curve) component.

f(x) = \frac{a}{1 + b\cdot \mathrm{exp}\left[-c
    \left((x - x_0\right)\right]}

Variable

Parameter

A

a

b

b

c

c

x_0

origin

Parameters
  • a (Float) – The curve’s maximum y-value, \mathrm{lim}_{x\to\infty}\left(y\right) = a

  • b (Float) – Additional parameter: b>1 shifts origin to larger values; 0<b<1 shifts origin to smaller values; b<0 introduces an asymptote

  • c (Float) – Logistic growth rate or steepness of the curve

  • origin (Float) – Position of the sigmoid’s midpoint

  • **kwargs – Extra keyword arguments are passed to the Expression component.