PegasusSolver (Apache Commons Math 4.0-SNAPSHOT)

java.lang.Object
- org.apache.commons.math4.legacy.analysis.solvers.BaseAbstractUnivariateSolver<UnivariateFunction>
- - org.apache.commons.math4.legacy.analysis.solvers.AbstractUnivariateSolver
  - - org.apache.commons.math4.legacy.analysis.solvers.BaseSecantSolver
    - - org.apache.commons.math4.legacy.analysis.solvers.PegasusSolver

All Implemented Interfaces:

BaseUnivariateSolver<UnivariateFunction>, BracketedUnivariateSolver<UnivariateFunction>, UnivariateSolver
```
public class PegasusSolver
extends BaseSecantSolver
```
Implements the Pegasus method for root-finding (approximating a zero of a univariate real function). It is a modified Regula Falsi method.
Like the Regula Falsi method, convergence is guaranteed by maintaining a bracketed solution. The Pegasus method however, should converge much faster than the original Regula Falsi method. Furthermore, this implementation of the Pegasus method should not suffer from the same implementation issues as the Regula Falsi method, which may fail to convergence in certain cases. Also, the Pegasus method should converge faster than the Illinois method, another Regula Falsi-based method.

The Pegasus method assumes that the function is continuous, but not necessarily smooth.

Implementation based on the following article: M. Dowell and P. Jarratt, The "Pegasus" method for computing the root of an equation, BIT Numerical Mathematics, volume 12, number 4, pages 503-508, Springer, 1972.

Since:

3.0

Nested Class Summary
- Nested classes/interfaces inherited from class org.apache.commons.math4.legacy.analysis.solvers.BaseSecantSolver
  BaseSecantSolver.Method

Field Summary
- Fields inherited from class org.apache.commons.math4.legacy.analysis.solvers.BaseSecantSolver
  DEFAULT_ABSOLUTE_ACCURACY

Constructor Summary

Constructors
Constructor	Description
`PegasusSolver()`	Construct a solver with default accuracy (1e-6).
`PegasusSolver(double absoluteAccuracy)`	Construct a solver.
`PegasusSolver(double relativeAccuracy, double absoluteAccuracy)`	Construct a solver.
`PegasusSolver(double relativeAccuracy, double absoluteAccuracy, double functionValueAccuracy)`	Construct a solver.

Method Summary
- Methods inherited from class org.apache.commons.math4.legacy.analysis.solvers.BaseSecantSolver
  doSolve, solve, solve, solve
- Methods inherited from class org.apache.commons.math4.legacy.analysis.solvers.BaseAbstractUnivariateSolver
  computeObjectiveValue, getAbsoluteAccuracy, getEvaluations, getFunctionValueAccuracy, getMax, getMaxEvaluations, getMin, getRelativeAccuracy, getStartValue, incrementEvaluationCount, isBracketing, isSequence, setup, solve, solve, verifyBracketing, verifyInterval, verifySequence
- Methods inherited from class java.lang.Object
  clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
- Methods inherited from interface org.apache.commons.math4.legacy.analysis.solvers.BaseUnivariateSolver
  getAbsoluteAccuracy, getEvaluations, getFunctionValueAccuracy, getMaxEvaluations, getRelativeAccuracy, solve, solve

- Constructor Detail
  - PegasusSolver
```
public PegasusSolver()
```
    Construct a solver with default accuracy (1e-6).
  - PegasusSolver
```
public PegasusSolver(double absoluteAccuracy)
```
    Construct a solver.
    
    Parameters:
    
    absoluteAccuracy - Absolute accuracy.
  - PegasusSolver
```
public PegasusSolver(double relativeAccuracy,
                     double absoluteAccuracy)
```
    Construct a solver.
    
    Parameters:
    
    relativeAccuracy - Relative accuracy.
    
    absoluteAccuracy - Absolute accuracy.
  - PegasusSolver
```
public PegasusSolver(double relativeAccuracy,
                     double absoluteAccuracy,
                     double functionValueAccuracy)
```
    Construct a solver.
    
    Parameters:
    
    relativeAccuracy - Relative accuracy.
    
    absoluteAccuracy - Absolute accuracy.
    
    functionValueAccuracy - Maximum function value error.