edu.rit.numeric

Class Quadratic

java.lang.Object

edu.rit.numeric.Quadratic

public class Quadratic
extends java.lang.Object

Class Quadratic solves for the real roots of a quadratic equation with real coefficients. The quadratic equation is of the form

ax² + bx + c = 0

To solve a quadratic equation, construct an instance of class Quadratic; call the Quadratic object's solve() method, passing in the coefficients a, b, and c; and obtain the roots from the Quadratic object's fields. The number of (real) roots, either 0 or 2, is stored in field nRoots. If there are no roots, fields x1 and x2 are set to NaN. If there are two roots, they are stored in fields x1 and x2 in descending order.

The same Quadratic object may be used to solve several quadratic equations. Each time the solve() method is called, the solution is stored in the Quadratic object's fields.

The formulas for the roots of a quadratic equation come from:

E. Weisstein. "Quadratic equation." From MathWorld--A Wolfram Web Resource. http://mathworld.wolfram.com/QuadraticEquation.html

Field Summary

Fields

Modifier and Type	Field and Description
int	nRoots The number of real roots.
double	x1 The first real root.
double	x2 The second real root.

Constructor Summary

Constructors

Constructor and Description
Quadratic() Construct a new Quadratic object.

Method Summary

Modifier and Type	Method and Description
static void	main(java.lang.String[] args) Unit test main program.
void	solve(double a, double b, double c) Solve the quadratic equation with the given coefficients.

Methods inherited from class java.lang.Object

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

Field Detail

nRoots

public int nRoots

The number of real roots.

x1

public double x1

The first real root.

x2

public double x2

The second real root.

Constructor Detail

Quadratic

public Quadratic()

Construct a new Quadratic object.

Method Detail

solve

public void solve(double a,
                  double b,
                  double c)

Solve the quadratic equation with the given coefficients. The results are stored in this Quadratic object's fields.

Parameters:

a - Coefficient of x².

b - Coefficient of x.

c - Constant coefficient.

Throws:

DomainException - (unchecked exception) Thrown if a is 0; in other words, the coefficients do not represent a quadratic equation.

main

public static void main(java.lang.String[] args)
                 throws java.lang.Exception

Unit test main program.

Usage: java edu.rit.numeric.Quadratic a b c

Throws:

java.lang.Exception