net.aerith.misao.util
Class SimultaneousEquation

java.lang.Object
  |
  +--net.aerith.misao.util.SimultaneousEquation

public class SimultaneousEquation

extends java.lang.Object

The SimultaneousEquation represents a simultaneous equation. It has a function to solve the equation.

For example, in the case of the simultaneous equations:

     a x + b y + c = 0
     d x + e y + f = 0
 

the coefficient matrix will be set as:

     SimultaneousEquation se = new SimultaneousEquation(2);
     se.coef[0][0] = a;
     se.coef[0][1] = b;
     se.coef[0][2] = c;
     se.coef[1][0] = d;
     se.coef[1][1] = e;
     se.coef[1][2] = f;
 

and the answer will be obtained as:

     se.solve();
     x = se.getAnswer(0);
     y = se.getAnswer(1);
 

Note that this class does not support the case that a coefficient is 0.

Field Summary

double[][]	coef The coefficient matrix.
protected int	dimension The dimension of the equations, which is the number of variables, or the number of equations.

Constructor Summary

SimultaneousEquation(int dimension)
Constructs a default SimultaneousEquation, with the number of equations.

Method Summary

double	getAnswer(int i) Gets the answer of i-th variable.
void	solve() Solves this simultaneous equation.
private void	solve(int k) Solves the specified equation in this simultaneous equation.

Methods inherited from class java.lang.Object

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

Field Detail

coef

public double[][] coef

The coefficient matrix. The number of rows is dimension and the number of columns is dimension + 1. The right edge term of each equation i, coef[i][dimension], is a constant term.

dimension

protected int dimension

The dimension of the equations, which is the number of variables, or the number of equations.

Constructor Detail

SimultaneousEquation

public SimultaneousEquation(int dimension)

Constructs a default SimultaneousEquation, with the number of equations. All the values in the coefficient matrix are set as 0.

Parameters:

dimension - the number of equations.

Method Detail

getAnswer

public double getAnswer(int i)

Gets the answer of i-th variable. Before to invoke this method, the method solve must be invoked.

Parameters:

i - the index of variable to get the answer.

solve

public void solve()

Solves this simultaneous equation. The answer of the i-th equation will be in coef[i][i+1].

Note that this method does not support the case that a coefficient is 0.

solve

private void solve(int k)

Solves the specified equation in this simultaneous equation. This method is invoked recurrsively.

Parameters:

k - the index of equation to solve.