/******************************************************************************
 * Program to print the frequences in the Chromatic Scale.
 * 
 * Copyright © 2017 Richard Lesh.  All rights reserved.
 *****************************************************************************/

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.pureprogrammer.Utils;

public class ChromaticScale {

    static final double A0_FREQUENCY = 27.5;
    static List<String> CHROMATIC_SCALE = Utils.listFromStrings(new String[]{"A", "A#", "B", "C", "C#", "D", "D#", "E", "F", "F#", "G", "G#"});
    static final String OUTPUT_FMT = "{0:s}{1:d} = {2:.4f} Hz";

    public static void main(String[] args) {
        int octave = 4;
        if (args.length == 1) {
            octave = Utils.stoiWithDefault(args[0], 0);
        }

        final double HALF_STEP = Math.pow(2.0, 1.0 / 12.0);
        double frequency = A0_FREQUENCY;
        if (octave > 0) {
            frequency *= Math.pow(2.0, octave);
        }
        for (int i = 0; i < 12; ++i) {
            if (CHROMATIC_SCALE.get(i).equals("C") ) {
                ++octave;
            }
            System.out.println(Utils.format(OUTPUT_FMT, CHROMATIC_SCALE.get(i), octave, frequency));
            frequency *= HALF_STEP;
        }
        System.out.println(Utils.format(OUTPUT_FMT, CHROMATIC_SCALE.get(0), octave, frequency));
    }
}