maspack.util

Class QuadraticSolver

java.lang.Object

maspack.util.QuadraticSolver

public class QuadraticSolver
extends java.lang.Object

Finds the real roots of a quadratic equation, attempting to handle numerical issues as best as possible.

Constructor Summary

Constructors

Constructor and Description
QuadraticSolver()

Method Summary

Modifier and Type	Method and Description
static int	getRoots(double[] roots, double a, double b, double c) Find the real roots of the quadratic equation
static int	getRoots(double[] roots, double a, double b, double c, double xlo, double xhi) Find the real roots of the quadratic equation

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

QuadraticSolver

public QuadraticSolver()

Method Detail

getRoots

public static int getRoots(double[] roots,
                           double a,
                           double b,
                           double c)

Find the real roots of the quadratic equation

    a x^2 + b x + c = 0
 

There will be either 0, 1, or 2 roots, where the single root case occurs when a = 0 or when there is a repeated root. When there are two roots, they are sorted in increasing order.

Parameters:

roots - returns the roots, must have length >= 2

a - first coefficient

b - second coefficient

c - third coefficient

Returns:

number of roots found

getRoots

public static int getRoots(double[] roots,
                           double a,
                           double b,
                           double c,
                           double xlo,
                           double xhi)

Find the real roots of the quadratic equation

    a x^2 + b x + c = 0
 

that lie within the interval [xlo, xhi]. There will be either 0, 1, or 2 roots, where the single root case occurs when a = 0 or when there is a repeated root. When there are two roots, they are sorted in increasing order.

Parameters:

roots - returns the roots, must have length >= 2

a - first coefficient

b - second coefficient

c - third coefficient

xlo - lower bound on x

xhi - upper bound on x

Returns:

number of roots found