## org.apache.commons.math3.analysis.solvers Class LaguerreSolver

```java.lang.Object
org.apache.commons.math3.analysis.solvers.BaseAbstractUnivariateSolver<PolynomialFunction>
org.apache.commons.math3.analysis.solvers.AbstractPolynomialSolver
org.apache.commons.math3.analysis.solvers.LaguerreSolver
```
All Implemented Interfaces:
BaseUnivariateSolver<PolynomialFunction>, PolynomialSolver

`public class LaguerreSolverextends AbstractPolynomialSolver`

Implements the Laguerre's Method for root finding of real coefficient polynomials. For reference, see A First Course in Numerical Analysis ISBN 048641454X, chapter 8. Laguerre's method is global in the sense that it can start with any initial approximation and be able to solve all roots from that point. The algorithm requires a bracketing condition.

Since:
1.2
Version:
\$Id: LaguerreSolver.java 1422195 2012-12-15 06:45:18Z psteitz \$

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

Method Summary
` double` `doSolve()`
Method for implementing actual optimization algorithms in derived classes.
` double` ```laguerre(double lo, double hi, double fLo, double fHi)```
Deprecated. This method should not be part of the public API: It will be made private in version 4.0.
` Complex[]` ```solveAllComplex(double[] coefficients, double initial)```
Find all complex roots for the polynomial with the given coefficients, starting from the given initial value.
` Complex` ```solveComplex(double[] coefficients, double initial)```
Find a complex root for the polynomial with the given coefficients, starting from the given initial value.

Methods inherited from class org.apache.commons.math3.analysis.solvers.AbstractPolynomialSolver
`getCoefficients, setup`

Methods inherited from class org.apache.commons.math3.analysis.solvers.BaseAbstractUnivariateSolver
`computeObjectiveValue, getAbsoluteAccuracy, getEvaluations, getFunctionValueAccuracy, getMax, getMaxEvaluations, getMin, getRelativeAccuracy, getStartValue, incrementEvaluationCount, isBracketing, isSequence, solve, 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.math3.analysis.solvers.BaseUnivariateSolver
`getAbsoluteAccuracy, getEvaluations, getFunctionValueAccuracy, getMaxEvaluations, getRelativeAccuracy, solve, solve, solve`

Constructor Detail

### LaguerreSolver

`public LaguerreSolver()`
Construct a solver with default accuracy (1e-6).

### LaguerreSolver

`public LaguerreSolver(double absoluteAccuracy)`
Construct a solver.

Parameters:
`absoluteAccuracy` - Absolute accuracy.

### LaguerreSolver

```public LaguerreSolver(double relativeAccuracy,
double absoluteAccuracy)```
Construct a solver.

Parameters:
`relativeAccuracy` - Relative accuracy.
`absoluteAccuracy` - Absolute accuracy.

### LaguerreSolver

```public LaguerreSolver(double relativeAccuracy,
double absoluteAccuracy,
double functionValueAccuracy)```
Construct a solver.

Parameters:
`relativeAccuracy` - Relative accuracy.
`absoluteAccuracy` - Absolute accuracy.
`functionValueAccuracy` - Function value accuracy.
Method Detail

### doSolve

```public double doSolve()
throws TooManyEvaluationsException,
NumberIsTooLargeException,
NoBracketingException```
Method for implementing actual optimization algorithms in derived classes.

Specified by:
`doSolve` in class `BaseAbstractUnivariateSolver<PolynomialFunction>`
Returns:
the root.
Throws:
`TooManyEvaluationsException` - if the maximal number of evaluations is exceeded.
`NoBracketingException` - if the initial search interval does not bracket a root and the solver requires it.
`NumberIsTooLargeException`

### laguerre

```@Deprecated
public double laguerre(double lo,
double hi,
double fLo,
double fHi)```
Deprecated. This method should not be part of the public API: It will be made private in version 4.0.

Find a real root in the given interval. Despite the bracketing condition, the root returned by `LaguerreSolver.ComplexSolver.solve(Complex[],Complex)` may not be a real zero inside `[min, max]`. For example, `p(x) = x3 + 1,` with `min = -2`, `max = 2`, `initial = 0`. When it occurs, this code calls `LaguerreSolver.ComplexSolver.solveAll(Complex[],Complex)` in order to obtain all roots and picks up one real root.

Parameters:
`lo` - Lower bound of the search interval.
`hi` - Higher bound of the search interval.
`fLo` - Function value at the lower bound of the search interval.
`fHi` - Function value at the higher bound of the search interval.
Returns:
the point at which the function value is zero.

### solveAllComplex

```public Complex[] solveAllComplex(double[] coefficients,
double initial)
throws NullArgumentException,
NoDataException,
TooManyEvaluationsException```
Find all complex roots for the polynomial with the given coefficients, starting from the given initial value.
Note: This method is not part of the API of `BaseUnivariateSolver`.

Parameters:
`coefficients` - Polynomial coefficients.
`initial` - Start value.
Returns:
the point at which the function value is zero.
Throws:
`TooManyEvaluationsException` - if the maximum number of evaluations is exceeded.
`NullArgumentException` - if the `coefficients` is `null`.
`NoDataException` - if the `coefficients` array is empty.
Since:
3.1

### solveComplex

```public Complex solveComplex(double[] coefficients,
double initial)
throws NullArgumentException,
NoDataException,
TooManyEvaluationsException```
Find a complex root for the polynomial with the given coefficients, starting from the given initial value.
Note: This method is not part of the API of `BaseUnivariateSolver`.

Parameters:
`coefficients` - Polynomial coefficients.
`initial` - Start value.
Returns:
the point at which the function value is zero.
Throws:
`TooManyEvaluationsException` - if the maximum number of evaluations is exceeded.
`NullArgumentException` - if the `coefficients` is `null`.
`NoDataException` - if the `coefficients` array is empty.
Since:
3.1