org.opentrafficsim.core.math

Class Solver

java.lang.Object

org.opentrafficsim.core.math.Solver

public final class Solver
extends Object

Solvers for simple equations.

Copyright (c) 2013-2019 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved.
BSD-style license. See OpenTrafficSim License.

Version:

$Revision$, $LastChangedDate$, by $Author$, initial version Dec 10, 2015

Author:

Alexander Verbraeck, Peter Knoppers

Method Summary

Modifier and Type	Method and Description
static double	firstSolutionAfter(double lowerBound, double a, double b, double c) Solve a quadratic or linear equation and return the solution that is closest (but not less than) a boundary.
static double[]	solve(double a, double b) Solve linear equation ax+b=0 for x.
static double[]	solve(double a, double b, double c) Solve quadratic equation ax2+bx+c=0 for x.

Methods inherited from class java.lang.Object

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

Method Detail

solve

public static double[] solve(double a,
                             double b,
                             double c)

Solve quadratic equation ax²+bx+c=0 for x. Degenerate case a == 0 is allowed.

Parameters:

a - double; the coefficient of x²

b - double; the coefficient of x

c - double;

Returns:

double[]; array with zero, one, or two elements (depending on the number of solutions of the equation)

firstSolutionAfter

public static double firstSolutionAfter(double lowerBound,
                                        double a,
                                        double b,
                                        double c)
                                 throws ValueException

Solve a quadratic or linear equation and return the solution that is closest (but not less than) a boundary.

Parameters:

lowerBound - double; minimum value of good solution

a - double; quadratic coefficient

b - double; linear coefficient

c - double; value of the quadratic function for x==0

Returns:

double; the solution that is closest (but not less than) a boundary

Throws:

ValueException - if there is no acceptable solution

solve

public static double[] solve(double a,
                             double b)

Solve linear equation ax+b=0 for x.

Parameters:

a - double; the coefficient of x

b - double;

Returns:

double[]; array with one or zero elements (depending on the number of solutions of the equation). The case where both a and b are zero returns an array of length 0.