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.