/*
 * $Id$
 *
 * This file is part of the Cloud Services Integration Platform (CSIP),
 * a Model-as-a-Service framework, API and application suite.
 *
 * 2012-2022, Olaf David and others, OMSLab, Colorado State University.
 *
 * OMSLab licenses this file to you under the MIT license.
 * See the LICENSE file in the project root for more information.
 */
package csip.cosu;

/**
 *
 */
class NSLOG2 extends ObjFunc {

  @Override
  public String name() {
    return "NSLOG2";
  }


  @Override
  public double eval(double[] obs, double[] sim, double missing) {
    checkArrays(sim, obs);
    double pow = 2;
    double rsme = 0;
    double var = 0;
    double avg = 0;
    double count = 0;
    for (int i = 0; i < obs.length; i++) {
      if (obs[i] > 0 && obs[i] != missing) {
        avg += Math.log(obs[i]);
        count += 1;
      }
    }
    avg /= count;
    for (int i = 0; i < obs.length; i++) {
      if (obs[i] > 0 && sim[i] > 0 && obs[i] != missing) {
        rsme += Math.pow(Math.abs(Math.log(obs[i]) - Math.log(sim[i])), pow);
        var += Math.pow(Math.abs(Math.log(obs[i]) - avg), pow);
      }
    }
    double result = 1.0 - (rsme / var);
    if (Double.isNaN(result))
      result = 0;
    return result;
  }


  @Override
  public int direction() {
    return 1;
  }


  @Override
  public int optimum() {
    return 1;
  }
  
}