Class Sigmoid
- java.lang.Object
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- org.apache.commons.math3.analysis.function.Sigmoid
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- All Implemented Interfaces:
DifferentiableUnivariateFunction
,UnivariateDifferentiableFunction
,UnivariateFunction
public class Sigmoid extends java.lang.Object implements UnivariateDifferentiableFunction, DifferentiableUnivariateFunction
Sigmoid function. It is the inverse of thelogit
function. A more flexible version, the generalised logistic, is implemented by theLogistic
class.- Since:
- 3.0
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
Sigmoid.Parametric
Parametric function where the input array contains the parameters of thesigmoid function
, ordered as follows: Lower asymptote Higher asymptote
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods Modifier and Type Method Description UnivariateFunction
derivative()
Deprecated.as of 3.1, replaced byvalue(DerivativeStructure)
double
value(double x)
Compute the value of the function.private static double
value(double x, double lo, double hi)
DerivativeStructure
value(DerivativeStructure t)
Simple mathematical function.
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Method Detail
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derivative
@Deprecated public UnivariateFunction derivative()
Deprecated.as of 3.1, replaced byvalue(DerivativeStructure)
Returns the derivative of the function- Specified by:
derivative
in interfaceDifferentiableUnivariateFunction
- Returns:
- the derivative function
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value
public double value(double x)
Compute the value of the function.- Specified by:
value
in interfaceUnivariateFunction
- Parameters:
x
- Point at which the function value should be computed.- Returns:
- the value of the function.
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value
private static double value(double x, double lo, double hi)
- Parameters:
x
- Value at which to compute the sigmoid.lo
- Lower asymptote.hi
- Higher asymptote.- Returns:
- the value of the sigmoid function at
x
.
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value
public DerivativeStructure value(DerivativeStructure t) throws DimensionMismatchException
Simple mathematical function.UnivariateDifferentiableFunction
classes compute both the value and the first derivative of the function.- Specified by:
value
in interfaceUnivariateDifferentiableFunction
- Parameters:
t
- function input value- Returns:
- function result
- Throws:
DimensionMismatchException
- if t is inconsistent with the function's free parameters or order- Since:
- 3.1
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