com.numericalmethod.suanshu.analysis.differentiation.univariate

Class Dfdx

java.lang.Object

com.numericalmethod.suanshu.analysis.function.rn2r1.univariate.UnivariateRealFunction

com.numericalmethod.suanshu.analysis.differentiation.univariate.Dfdx

All Implemented Interfaces:

Function<Vector,java.lang.Double>, RealScalarFunction, java.io.Serializable

public class Dfdx
extends UnivariateRealFunction

The first derivative is a measure of how a function changes as its input changes. In other words, a derivative is how much a quantity changes if the input changes (by a very small amount). The derivative of a function at a particular point is the best linear approximation of the function at that point. For a univariate real function, the derivative at a point is the slope of the tangent line to the function at that point.

This implementation is a simple wrapper class around the built-in derivative functions, e.g., DBeta, DErf, and the numerical derivative computation classes, e.g., FiniteDifference and Ridders.

See Also:

Wikipedia: Derivative, FiniteDifference, Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Dfdx.Method the methods available to compute the numerical derivative

Nested classes/interfaces inherited from interface com.numericalmethod.suanshu.analysis.function.Function

Function.EvaluationException

Constructor Summary

Constructors

Constructor and Description
Dfdx(UnivariateRealFunction f) Construct, using the central finite difference, the first order derivative function of a univariate function f.
Dfdx(UnivariateRealFunction f, Dfdx.Method method) Construct the first order derivative function of a univariate function f.

Method Summary

Modifier and Type	Method and Description
double	evaluate(double x) Evaluate y = f(x).

Methods inherited from class com.numericalmethod.suanshu.analysis.function.rn2r1.univariate.UnivariateRealFunction

dimensionOfDomain, dimensionOfRange, evaluate

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Dfdx

public Dfdx(UnivariateRealFunction f,
            Dfdx.Method method)

Construct the first order derivative function of a univariate function f.

Parameters:

f - a univariate function

method - the numerical method to use, c.f., Dfdx.Method

Dfdx

public Dfdx(UnivariateRealFunction f)

Construct, using the central finite difference, the first order derivative function of a univariate function f.

Parameters:

f - a univariate function

Method Detail

evaluate

public double evaluate(double x)

Description copied from class: UnivariateRealFunction

Evaluate y = f(x).

Specified by:

evaluate in class UnivariateRealFunction

Parameters:

x - x

Returns:

f(x)