package joptima.functions;

import joptima.Parameter;

/**
 * Function amplitude * cos(2 * pi * frequency * (x - offset)).
 * A concrete implementation of joptima.Function that calculates
 * a cosine.
 */
public class Cosine extends ConstrainableFunction {

  public double m_amplitude, m_frequency, m_xoffset;

  public Parameter[] getParameters() {
    Parameter[] parameters = new Parameter[countUnconstrained()];
    try {
      int cursor = 0;
      if (!m_constrained[0]) parameters[cursor++] = new Parameter(this, "amplitude");
      if (!m_constrained[1]) parameters[cursor++] = new Parameter(this, "frequency");
      if (!m_constrained[2]) parameters[cursor++] = new Parameter(this, "xoffset");
    } catch (NoSuchFieldException nsfe) {
      nsfe.printStackTrace();
    }
    return parameters;
  }

  public void constrain(String parametername) {
    if ("amplitude".equals(parametername)) m_constrained[0] = true;
    if ("frequency".equals(parametername)) m_constrained[1] = true;
    if ("xoffset".equals(parametername)) m_constrained[2] = true;
  }

  private String m_name = "Cosine";
  public String getName() { return m_name; }
  public void setName(String newname) { m_name = newname; }

  /**
   * Default constructor: amplitude = 1, frequency = 1, xoffset = 0.
   */
  public Cosine() {
    this(1, 1, 0);
  }

  /**
   * Constructor.
   */
  public Cosine(double amplitude, double frequency, double xoffset) {
    this.m_amplitude = amplitude;
    this.m_frequency = frequency;
    this.m_xoffset = xoffset;
    m_constrained = new boolean[3];
  }

  public double calculate(double x) {
    return m_amplitude * Math.cos(2 * Math.PI * m_frequency * (x - m_xoffset));
  }

  public void setAngularFrequency(double omega) {
    m_frequency = omega / Math.PI / 2;
  }

  public double getAngularFrequency() {
    return 2 * Math.PI * m_frequency;
  }

  public double getAmplitude() {
    return m_amplitude;
  }

  public void setAmplitude(double amplitude) {
    this.m_amplitude = amplitude;
  }

  public double getFrequency() {
    return m_frequency;
  }

  public void setFrequency(double frequency) {
    this.m_frequency = frequency;
  }

  public double getXoffset() {
    return m_xoffset;
  }

  public void setXoffset(double xoffset) {
    this.m_xoffset = xoffset;
  }
}