Fourier Stuff

CoefficientTable.java

package tterrag.fourier;

import lombok.Getter;
import lombok.RequiredArgsConstructor;

public class CoefficientTable
{
    @Getter
    @RequiredArgsConstructor
    public static class Pair
    {
        private final double a, b;
    }

    private Pair[] coefts;

    public CoefficientTable(int m)
    {
        coefts = new Pair[m];
    }

    public void addCoefts(int n, double a, double b)
    {
        coefts[n - 1] = new Pair(a, b);
    }

    public Pair getDataFor(int n)
    {
        return coefts[n - 1];
    }

    public double getAFor(int n)
    {
        return getDataFor(n).getA();
    }

    public double getBFor(int n)
    {
        return getDataFor(n).getB();
    }
}

FourierFunction.java

package tterrag.fourier;

import lombok.RequiredArgsConstructor;

@RequiredArgsConstructor
public class FourierFunction
{
    private final double a0;
    private final CoefficientTable table;

    public double compute(double x, int n)
    {
        return (a0 / 2) + calcA(x, n) + calcB(x, n);
    }

    private double calcA(double x, int n)
    {
        double ret = 0;
        for (int i = n; i > 0; i--)
        {
            ret += table.getAFor(i) * Math.cos(i * Math.PI * x);
        }
        return ret;
    }

    private double calcB(double x, int n)
    {
        double ret = 0;
        for (int i = n; i > 0; i--)
        {
            ret += table.getBFor(i) * Math.sin(i * Math.PI * x);
        }
        return ret;
    }
}