ActivationStep DerivativeFunction Method Encog Machine Learning Framework for .Net
Calculate the derivative. For performance reasons two numbers are provided. First, the value "b" is simply the number that we would like to calculate the derivative of. Second, the value "a", which is the value returned by the activation function, when presented with "b". We use two values because some of the most common activation functions make use of the result of the activation function. It is bad for performance to calculate this value twice. Yet, not all derivatives are calculated this way. By providing both the value before the activation function is applied ("b"), and after the activation function is applied("a"), the class can be constructed to use whichever value will be the most efficient.

Namespace: Encog.Engine.Network.Activation
Assembly: encog-core-cs (in encog-core-cs.dll) Version: (

public virtual double DerivativeFunction(
	double b,
	double a


Type: System Double
The number to calculate the derivative of, the number "before" the activation function was applied.
Type: System Double
The number "after" an activation function has been applied. @return The derivative.

Return Value

Type: Double

[Missing <returns> documentation for "M:Encog.Engine.Network.Activation.ActivationStep.DerivativeFunction(System.Double,System.Double)"]


IActivationFunction DerivativeFunction(Double, Double)
See Also