org.apache.commons.math3.ode.sampling

## Class FieldStepNormalizer<T extends RealFieldElement<T>>

- java.lang.Object
- - org.apache.commons.math3.ode.sampling.FieldStepNormalizer<T>

- Type Parameters:
    `T` - the type of the field elements
  All Implemented Interfaces:
    FieldStepHandler<T>

      public class FieldStepNormalizer<T extends RealFieldElement<T>>
      extends Object
      implements FieldStepHandler<T>

  This class wraps an object implementing `FieldFixedStepHandler` into a `FieldStepHandler`.

  This wrapper allows to use fixed step handlers with general integrators which cannot guaranty their integration steps will remain constant and therefore only accept general step handlers.

  The stepsize used is selected at construction time. The `handleStep` method of the underlying `FieldFixedStepHandler` object is called at normalized times. The normalized times can be influenced by the `StepNormalizerMode` and `StepNormalizerBounds`.

  There is no constraint on the integrator, it can use any time step it needs (time steps longer or shorter than the fixed time step and non-integer ratios are all allowed).

  Examples (step size = 0.5)
  Start time | End time | Direction | `Mode` | `Bounds` | Output
  0.3 | 3.1 | forward | `INCREMENT` | `NEITHER` | 0.8, 1.3, 1.8, 2.3, 2.8
  0.3 | 3.1 | forward | `INCREMENT` | `FIRST` | 0.3, 0.8, 1.3, 1.8, 2.3, 2.8
  0.3 | 3.1 | forward | `INCREMENT` | `LAST` | 0.8, 1.3, 1.8, 2.3, 2.8, 3.1
  0.3 | 3.1 | forward | `INCREMENT` | `BOTH` | 0.3, 0.8, 1.3, 1.8, 2.3, 2.8, 3.1
  0.3 | 3.1 | forward | `MULTIPLES` | `NEITHER` | 0.5, 1.0, 1.5, 2.0, 2.5, 3.0
  0.3 | 3.1 | forward | `MULTIPLES` | `FIRST` | 0.3, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0
  0.3 | 3.1 | forward | `MULTIPLES` | `LAST` | 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.1
  0.3 | 3.1 | forward | `MULTIPLES` | `BOTH` | 0.3, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.1
  0.0 | 3.0 | forward | `INCREMENT` | `NEITHER` | 0.5, 1.0, 1.5, 2.0, 2.5, 3.0
  0.0 | 3.0 | forward | `INCREMENT` | `FIRST` | 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0
  0.0 | 3.0 | forward | `INCREMENT` | `LAST` | 0.5, 1.0, 1.5, 2.0, 2.5, 3.0
  0.0 | 3.0 | forward | `INCREMENT` | `BOTH` | 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0
  0.0 | 3.0 | forward | `MULTIPLES` | `NEITHER` | 0.5, 1.0, 1.5, 2.0, 2.5, 3.0
  0.0 | 3.0 | forward | `MULTIPLES` | `FIRST` | 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0
  0.0 | 3.0 | forward | `MULTIPLES` | `LAST` | 0.5, 1.0, 1.5, 2.0, 2.5, 3.0
  0.0 | 3.0 | forward | `MULTIPLES` | `BOTH` | 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0
  3.1 | 0.3 | backward | `INCREMENT` | `NEITHER` | 2.6, 2.1, 1.6, 1.1, 0.6
  3.1 | 0.3 | backward | `INCREMENT` | `FIRST` | 3.1, 2.6, 2.1, 1.6, 1.1, 0.6
  3.1 | 0.3 | backward | `INCREMENT` | `LAST` | 2.6, 2.1, 1.6, 1.1, 0.6, 0.3
  3.1 | 0.3 | backward | `INCREMENT` | `BOTH` | 3.1, 2.6, 2.1, 1.6, 1.1, 0.6, 0.3
  3.1 | 0.3 | backward | `MULTIPLES` | `NEITHER` | 3.0, 2.5, 2.0, 1.5, 1.0, 0.5
  3.1 | 0.3 | backward | `MULTIPLES` | `FIRST` | 3.1, 3.0, 2.5, 2.0, 1.5, 1.0, 0.5
  3.1 | 0.3 | backward | `MULTIPLES` | `LAST` | 3.0, 2.5, 2.0, 1.5, 1.0, 0.5, 0.3
  3.1 | 0.3 | backward | `MULTIPLES` | `BOTH` | 3.1, 3.0, 2.5, 2.0, 1.5, 1.0, 0.5, 0.3
  3.0 | 0.0 | backward | `INCREMENT` | `NEITHER` | 2.5, 2.0, 1.5, 1.0, 0.5, 0.0
  3.0 | 0.0 | backward | `INCREMENT` | `FIRST` | 3.0, 2.5, 2.0, 1.5, 1.0, 0.5, 0.0
  3.0 | 0.0 | backward | `INCREMENT` | `LAST` | 2.5, 2.0, 1.5, 1.0, 0.5, 0.0
  3.0 | 0.0 | backward | `INCREMENT` | `BOTH` | 3.0, 2.5, 2.0, 1.5, 1.0, 0.5, 0.0
  3.0 | 0.0 | backward | `MULTIPLES` | `NEITHER` | 2.5, 2.0, 1.5, 1.0, 0.5, 0.0
  3.0 | 0.0 | backward | `MULTIPLES` | `FIRST` | 3.0, 2.5, 2.0, 1.5, 1.0, 0.5, 0.0
  3.0 | 0.0 | backward | `MULTIPLES` | `LAST` | 2.5, 2.0, 1.5, 1.0, 0.5, 0.0
  3.0 | 0.0 | backward | `MULTIPLES` | `BOTH` | 3.0, 2.5, 2.0, 1.5, 1.0, 0.5, 0.0

  Since:
    3.6
  See Also:
    `FieldStepHandler`, `FieldFixedStepHandler`, `StepNormalizerMode`, `StepNormalizerBounds`

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `FieldStepNormalizer(double h, FieldFixedStepHandler<T> handler)` Simple constructor.
    `FieldStepNormalizer(double h, FieldFixedStepHandler<T> handler, StepNormalizerBounds bounds)` Simple constructor.
    `FieldStepNormalizer(double h, FieldFixedStepHandler<T> handler, StepNormalizerMode mode)` Simple constructor.
    `FieldStepNormalizer(double h, FieldFixedStepHandler<T> handler, StepNormalizerMode mode, StepNormalizerBounds bounds)` Simple constructor.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `handleStep(FieldStepInterpolator<T> interpolator, boolean isLast)` Handle the last accepted step
    `void` | `init(FieldODEStateAndDerivative<T> initialState, T finalTime)` Initialize step handler at the start of an ODE integration.

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

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

- - ### Constructor Detail

    - #### FieldStepNormalizer

          public FieldStepNormalizer(double h,
                             FieldFixedStepHandler<T> handler)

      Simple constructor. Uses `INCREMENT` mode, and `FIRST` bounds setting, for backwards compatibility.
      Parameters:
        `h` - fixed time step (sign is not used)
        `handler` - fixed time step handler to wrap

    - #### FieldStepNormalizer

          public FieldStepNormalizer(double h,
                             FieldFixedStepHandler<T> handler,
                             StepNormalizerMode mode)

      Simple constructor. Uses `FIRST` bounds setting.
      Parameters:
        `h` - fixed time step (sign is not used)
        `handler` - fixed time step handler to wrap
        `mode` - step normalizer mode to use
      Since:
        3.0

    - #### FieldStepNormalizer

          public FieldStepNormalizer(double h,
                             FieldFixedStepHandler<T> handler,
                             StepNormalizerBounds bounds)

      Simple constructor. Uses `INCREMENT` mode.
      Parameters:
        `h` - fixed time step (sign is not used)
        `handler` - fixed time step handler to wrap
        `bounds` - step normalizer bounds setting to use
      Since:
        3.0

    - #### FieldStepNormalizer

          public FieldStepNormalizer(double h,
                             FieldFixedStepHandler<T> handler,
                             StepNormalizerMode mode,
                             StepNormalizerBounds bounds)

      Simple constructor.
      Parameters:
        `h` - fixed time step (sign is not used)
        `handler` - fixed time step handler to wrap
        `mode` - step normalizer mode to use
        `bounds` - step normalizer bounds setting to use
      Since:
        3.0

  - ### Method Detail

    - #### init

          public void init(FieldODEStateAndDerivative<T> initialState,
                  T finalTime)

      Initialize step handler at the start of an ODE integration.

      This method is called once at the start of the integration. It may be used by the step handler to initialize some internal data if needed.

      Specified by:
        `init` in interface `FieldStepHandler<T extends RealFieldElement<T>>`
      Parameters:
        `initialState` - initial time, state vector and derivative
        `finalTime` - target time for the integration

    - #### handleStep

          public void handleStep(FieldStepInterpolator<T> interpolator,
                        boolean isLast)
                          throws MaxCountExceededException

      Handle the last accepted step
      Specified by:
        `handleStep` in interface `FieldStepHandler<T extends RealFieldElement<T>>`
      Parameters:
        `interpolator` - interpolator for the last accepted step. For efficiency purposes, the various integrators reuse the same object on each call, so if the instance wants to keep it across all calls (for example to provide at the end of the integration a continuous model valid throughout the integration range), it should build a local copy using the clone method and store this copy.
        `isLast` - true if the step is the last one
      Throws:
        `MaxCountExceededException` - if the interpolator throws one because the number of functions evaluations is exceeded

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