LambdaMethod (OREKIT 13.0 API)

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

All Implemented Interfaces:

IntegerLeastSquareSolver

Direct Known Subclasses:

IntegerBootstrapping
```
public class LambdaMethod
extends AbstractLambdaMethod
```
Decorrelation/reduction engine for LAMBDA method.
This class implements PJG Teunissen Least Square Ambiguity Decorrelation Adjustment (LAMBDA) method, as described in 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

It slightly departs on the original LAMBDA method as it does implement the following improvements proposed in the de Jonge and Tiberius 1996 paper that vastly speed up the search:
- alternate search starting from the middle and expanding outwards
- automatic shrinking of ellipsoid during the search
Since:

10.0

Author:

Luc Maisonobe

See Also:

AmbiguitySolver

Constructor Summary

Constructors
Constructor Description

LambdaMethod()
Empty constructor.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`protected void`	`discreteSearch()`	Find the best solutions to the Integer Least Square problem.
`protected void`	`inverseDecomposition()`	Inverse the decomposition.
`protected void`	`ltdlDecomposition()`	Perform Lᵀ.D.L = Q decomposition of the covariance matrix.
`protected void`	`reduction()`	Perform LAMBDA reduction.

Methods inherited from class org.orekit.estimation.measurements.gnss.AbstractLambdaMethod
addSolution, getDecorrelatedReference, getDiagReference, getLowReference, getMaxDistance, getMaxSolution, getSize, getSolutionsSize, getZInverseTransformationReference, integerGaussTransformation, lIndex, permutation, recoverAmbiguities, removeSolution, setComparator, solveILS, zIndex

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

- Constructor Detail
  - LambdaMethod
```
public LambdaMethod()
```
    Empty constructor.
    This constructor is not strictly necessary, but it prevents spurious javadoc warnings with JDK 18 and later.
    
    Since:
    
    12.0
- Method Detail
  - ltdlDecomposition
```
protected void ltdlDecomposition()
```
    Perform Lᵀ.D.L = Q decomposition of the covariance matrix.
    
    Specified by:
    
    ltdlDecomposition in class AbstractLambdaMethod
  - reduction
```
protected void reduction()
```
    Perform LAMBDA reduction.
    
    Specified by:
    
    reduction in class AbstractLambdaMethod
  - discreteSearch
```
protected void discreteSearch()
```
    Find the best solutions to the Integer Least Square problem.
    
    Specified by:
    
    discreteSearch in class AbstractLambdaMethod
  - inverseDecomposition
```
protected 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.
    
    Specified by:
    
    inverseDecomposition in class AbstractLambdaMethod