java.lang.Object
- org.orekit.estimation.measurements.gnss.AbstractLambdaMethod

All Implemented Interfaces:

IntegerLeastSquareSolver

Direct Known Subclasses:

LambdaMethod, ModifiedLambdaMethod
```
public abstract class AbstractLambdaMethod
extends Object
implements IntegerLeastSquareSolver
```
Base class for decorrelation/reduction engine for LAMBDA type methods.
This class is based on both the 1996 paper The LAMBDA method for integer ambiguity estimation: implementation aspects by Paul de Jonge and Christian Tiberius and on the 2005 paper A modified LAMBDA method for integer least-squares estimation by X.-W Chang, X. Yang and T. Zhou, Journal of Geodesy 79(9):552-565, DOI: 10.1007/s00190-005-0004-x

Since:

10.0

Author:

Luc Maisonobe

Constructor Summary

Constructors
Modifier Constructor Description

protected AbstractLambdaMethod()
Constructor.

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`protected void`	`addSolution(long[] fixed, double squaredNorm)`	Add a new solution.
`protected abstract void`	`discreteSearch()`	Find the best solutions to the Integer Least Square problem.
`protected double[]`	`getDecorrelatedReference()`	Get the reference decorrelated ambiguities.
`protected double[]`	`getDiagReference()`	Get a reference to the diagonal matrix of the decomposition.
`protected double[]`	`getLowReference()`	Get a reference to the lower triangular matrix of the decomposition.
`protected double`	`getMaxDistance()`	Get the maximum of distance among the solutions found.
`protected int`	`getMaxSolution()`	Get the maximum number of solutions seeked.
`protected int`	`getSize()`	Get the size of the problem.
`protected int`	`getSolutionsSize()`	Get the number of solutions found.
`protected int[]`	`getZInverseTransformationReference()`	Get a reference to the Z inverse transformation matrix.
`protected void`	`integerGaussTransformation(int row, int col)`	Perform one integer Gauss transformation.
`protected abstract void`	`inverseDecomposition()`	Inverse the decomposition.
`protected int`	`lIndex(int row, int col)`	Get the index of an entry in the lower triangular matrix.
`protected abstract void`	`ltdlDecomposition()`	Perform Lᵀ.D.L = Q decomposition of the covariance matrix.
`protected void`	`permutation(int k0, double delta)`	Perform one symmetric permutation involving rows/columns `k0` and `k0+1`.
`protected IntegerLeastSquareSolution[]`	`recoverAmbiguities()`	Recover ambiguities prior to the Z-transformation.
`protected abstract void`	`reduction()`	Perform LAMBDA reduction.
`protected void`	`removeSolution()`	Remove spurious solution.
`void`	`setComparator(Comparator<IntegerLeastSquareSolution> newCompartor)`	Set a custom comparator for integer least square solutions comparison.
`IntegerLeastSquareSolution[]`	`solveILS(int nbSol, double[] floatAmbiguities, int[] indirection, RealMatrix covariance)`	Find the best solutions to an Integer Least Square problem.
`protected int`	`zIndex(int row, int col)`	Get the index of an entry in the Z transformation matrix.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - AbstractLambdaMethod
```
protected AbstractLambdaMethod()
```
    Constructor.
    By default a IntegerLeastSquareComparator is used to compare integer least square solutions
- Method Detail
  - solveILS
```
public IntegerLeastSquareSolution[] solveILS(int nbSol,
                                             double[] floatAmbiguities,
                                             int[] indirection,
                                             RealMatrix covariance)
```
    Find the best solutions to an Integer Least Square problem.
    
    Specified by:
    
    solveILS in interface IntegerLeastSquareSolver
    
    Parameters:
    
    nbSol - number of solutions to search for
    
    floatAmbiguities - float estimates of ambiguities
    
    indirection - indirection array to extract ambiguity covariances from global covariance matrix
    
    covariance - global covariance matrix (includes ambiguities among other parameters)
    
    Returns:
    
    at most nbSol solutions a to the Integer Least Square problem, in increasing squared distance order
  - setComparator
```
public void setComparator(Comparator<IntegerLeastSquareSolution> newCompartor)
```
    Set a custom comparator for integer least square solutions comparison.
    Calling this method overrides any comparator that could have been set beforehand. It also overrides the default IntegerLeastSquareComparator.
    
    Parameters:
    
    newCompartor - new comparator to use
    
    Since:
    
    11.0
  - getDiagReference
```
protected double[] getDiagReference()
```
    Get a reference to the diagonal matrix of the decomposition.
    BEWARE: the returned value is a reference to an internal array, it is only intended for subclasses use (hence the method is protected and not public).
    
    Returns:
    
    reference to the diagonal matrix of the decomposition
  - getLowReference
```
protected double[] getLowReference()
```
    Get a reference to the lower triangular matrix of the decomposition.
    BEWARE: the returned value is a reference to an internal array, it is only intended for subclasses use (hence the method is protected and not public).
    
    Returns:
    
    reference to the lower triangular matrix of the decomposition
  - getDecorrelatedReference
```
protected double[] getDecorrelatedReference()
```
    Get the reference decorrelated ambiguities.
    
    Returns:
    
    reference to the decorrelated ambiguities.
  - getMaxSolution
```
protected int getMaxSolution()
```
    Get the maximum number of solutions seeked.
    
    Returns:
    
    the maximum number of solutions seeked
  - addSolution
```
protected void addSolution(long[] fixed,
                           double squaredNorm)
```
    Add a new solution.
    
    Parameters:
    
    fixed - solution array
    
    squaredNorm - squared distance to the corresponding float solution
  - removeSolution
```
protected void removeSolution()
```
    Remove spurious solution.
  - getSolutionsSize
```
protected int getSolutionsSize()
```
    Get the number of solutions found.
    
    Returns:
    
    the number of solutions found
  - getMaxDistance
```
protected double getMaxDistance()
```
    Get the maximum of distance among the solutions found. getting last of solutions as they are sorted in SortesSet
    
    Returns:
    
    greatest distance of the solutions
    
    Since:
    
    10.2
  - getZInverseTransformationReference
```
protected int[] getZInverseTransformationReference()
```
    Get a reference to the Z inverse transformation matrix.
    BEWARE: the returned value is a reference to an internal array, it is only intended for subclasses use (hence the method is protected and not public). BEWARE: for the MODIFIED LAMBDA METHOD, the returned matrix Z is such that Q = Z'L'DLZ where Q is the covariance matrix and ' refers to the transposition operation
    
    Returns:
    
    array of integer corresponding to Z matrix
    
    Since:
    
    10.2
  - getSize
```
protected int getSize()
```
    Get the size of the problem. In the ILS problem, the integer returned is the size of the covariance matrix.
    
    Returns:
    
    the size of the ILS problem
    
    Since:
    
    10.2
  - ltdlDecomposition
```
protected abstract void ltdlDecomposition()
```
    Perform Lᵀ.D.L = Q decomposition of the covariance matrix.
  - reduction
```
protected abstract void reduction()
```
    Perform LAMBDA reduction.
  - discreteSearch
```
protected abstract void discreteSearch()
```
    Find the best solutions to the Integer Least Square problem.
  - inverseDecomposition
```
protected abstract void inverseDecomposition()
```
    Inverse the decomposition.
    This method transforms the Lᵀ.D.L = Q decomposition of covariance into the L⁻¹.D⁻¹.L⁻ᵀ = Q⁻¹ decomposition of the inverse of covariance.
  - integerGaussTransformation
```
protected void integerGaussTransformation(int row,
                                          int col)
```
    Perform one integer Gauss transformation.
    This method corresponds to algorithm 2.1 in X.-W Chang, X. Yang and T. Zhou paper.
    
    Parameters:
    
    row - row index (counting from 0)
    
    col - column index (counting from 0)
  - permutation
```
protected void permutation(int k0,
                           double delta)
```
    Perform one symmetric permutation involving rows/columns k0 and k0+1.
    This method corresponds to algorithm 2.2 in X.-W Chang, X. Yang and T. Zhou paper.
    
    Parameters:
    
    k0 - diagonal index (counting from 0)
    
    delta - new value for diag[k0+1]
  - recoverAmbiguities
```
protected IntegerLeastSquareSolution[] recoverAmbiguities()
```
    Recover ambiguities prior to the Z-transformation.
    
    Returns:
    
    recovered ambiguities
  - lIndex
```
protected int lIndex(int row,
                     int col)
```
    Get the index of an entry in the lower triangular matrix.
    
    Parameters:
    
    row - row index (counting from 0)
    
    col - column index (counting from 0)
    
    Returns:
    
    index in the single dimension array
  - zIndex
```
protected int zIndex(int row,
                     int col)
```
    Get the index of an entry in the Z transformation matrix.
    
    Parameters:
    
    row - row index (counting from 0)
    
    col - column index (counting from 0)
    
    Returns:
    
    index in the single dimension array

Class AbstractLambdaMethod

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

AbstractLambdaMethod

Method Detail

solveILS

setComparator

getDiagReference

getLowReference

getDecorrelatedReference

getMaxSolution

addSolution

removeSolution

getSolutionsSize

getMaxDistance

getZInverseTransformationReference

getSize

ltdlDecomposition

reduction

discreteSearch

inverseDecomposition

integerGaussTransformation

permutation

recoverAmbiguities

lIndex

zIndex