/*
 * $Id$
 *
 * 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 TRMSE extends ObjFunc {

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


  @Override
  public double eval(double[] obs, double[] sim, double missing) {
    checkArrays(sim, obs);
    double error = 0;
    double z_pred = 0.;
    double z_val = 0.;
    int len = 0;
    for (int i = 0; i < sim.length; i++) {
      if (obs[i] > missing) {
        z_pred = (Math.pow(1.0 + sim[i], 0.3) - 1.0) / 0.3;
        z_val = (Math.pow(1.0 + obs[i], 0.3) - 1.0) / 0.3;
        error += (z_pred - z_val) * (z_pred - z_val);
        len++;
      }
    }
    if (len == 0)
      throw new RuntimeException("No valid len value.");
    return Math.sqrt(error / len);
  }


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


  @Override
  public int optimum() {
    return 0;
  }

}