DoubleSigmoidCurve Class

public class DoubleSigmoidCurve : NonlinearCurve

Public Class DoubleSigmoidCurve
	Inherits NonlinearCurve

public ref class DoubleSigmoidCurve : public NonlinearCurve

type DoubleSigmoidCurve = 
    class
        inherit NonlinearCurve
    end

Inheritance

Object  →  Curve  →  NonlinearCurve  →  DoubleSigmoidCurve

Use the DoubleSigmoidCurve class to represent a six-parameter curve that combines two sigmoid functions to model processes with a peak, such as enzyme activity versus pH or temperature, or other phenomena that increase to a maximum and then decrease.

The double sigmoid curve is the product of an ascending sigmoid (representing activation) and a descending sigmoid (representing deactivation or inhibition). This creates a bell-shaped curve that is useful when the underlying process has distinct onset and offset transitions.

The equation is:

Parameters:

• A – Maximum amplitude (peak height above baseline). See Amplitude.
• k₁ – Steepness of the rising phase. See RisingHillSlope.
• x₁ – Midpoint of the rising phase. See RisingCenter.
• k₂ – Steepness of the falling phase. See FallingHillSlope.
• x₂ – Midpoint of the falling phase. See FallingCenter.
• C – Baseline offset. See Offset.

Applications:

• Enzyme activity vs. pH or temperature
• Biological responses with optimal ranges
• Drug efficacy with therapeutic window
• Population dynamics with growth and decline phases
• Performance curves with fatigue or saturation

For details on how to fit a curve of this type, see the NonlinearCurveFitter class.

Reference