org.apache.commons.math3.analysis.function

## Class Identity

- java.lang.Object
- - org.apache.commons.math3.analysis.function.Identity

- All Implemented Interfaces:
    DifferentiableUnivariateFunction, UnivariateDifferentiableFunction, UnivariateFunction

      public class Identity
      extends Object
      implements UnivariateDifferentiableFunction, DifferentiableUnivariateFunction

  Identity function.
  Since:
    3.0

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `Identity()`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `DifferentiableUnivariateFunction` | `derivative()` Deprecated. as of 3.1, replaced by `value(DerivativeStructure)`
    `DerivativeStructure` | `value(DerivativeStructure t)` Simple mathematical function.
    `double` | `value(double x)` Compute the value of the function.

    - ### Methods inherited from class java.lang.Object

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

- - ### Constructor Detail

    - #### Identity

          public Identity()

  - ### Method Detail

    - #### value

          public double value(double x)

      Compute the value of the function.
      Specified by:
        `value` in interface `UnivariateFunction`
      Parameters:
        `x` - Point at which the function value should be computed.
      Returns:
        the value of the function.

    - #### derivative

          @Deprecated
          public DifferentiableUnivariateFunction derivative()

      Deprecated. as of 3.1, replaced by `value(DerivativeStructure)`
      Returns the derivative of the function
      Specified by:
        `derivative` in interface `DifferentiableUnivariateFunction`
      Returns:
        the derivative function

    - #### value

          public DerivativeStructure value(DerivativeStructure t)

      Simple mathematical function.

      `UnivariateDifferentiableFunction` classes compute both the value and the first derivative of the function.

      Specified by:
        `value` in interface `UnivariateDifferentiableFunction`
      Parameters:
        `t` - function input value
      Returns:
        function result
      Since:
        3.1

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