// ******************************************************************************
   //
   // Title:       Force Field X.
   // Description: Force Field X - Software for Molecular Biophysics.
   // Copyright:   Copyright (c) Michael J. Schnieders 2001-2024.
   //
   // This file is part of Force Field X.
   //
   // Force Field X is free software; you can redistribute it and/or modify it
  // under the terms of the GNU General Public License version 3 as published by
  // the Free Software Foundation.
  //
  // Force Field X is distributed in the hope that it will be useful, but WITHOUT
  // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  // FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
  // details.
  //
  // You should have received a copy of the GNU General Public License along with
  // Force Field X; if not, write to the Free Software Foundation, Inc., 59 Temple
  // Place, Suite 330, Boston, MA 02111-1307 USA
  //
  // Linking this library statically or dynamically with other modules is making a
  // combined work based on this library. Thus, the terms and conditions of the
  // GNU General Public License cover the whole combination.
  //
  // As a special exception, the copyright holders of this library give you
  // permission to link this library with independent modules to produce an
  // executable, regardless of the license terms of these independent modules, and
  // to copy and distribute the resulting executable under terms of your choice,
  // provided that you also meet, for each linked independent module, the terms
  // and conditions of the license of that module. An independent module is a
  // module which is not derived from or based on this library. If you modify this
  // library, you may extend this exception to your version of the library, but
  // you are not obligated to do so. If you do not wish to do so, delete this
  // exception statement from your version.
  //
  // ******************************************************************************
  package ffx.numerics.fft;
  
  import static org.junit.Assert.assertEquals;
  
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Random;
  
  import ffx.utilities.FFXTest;
  import org.junit.Before;
  import org.junit.Test;
  import org.junit.runner.RunWith;
  import org.junit.runners.Parameterized;
  import org.junit.runners.Parameterized.Parameters;
  
  /** @author Michael J. Schnieders */
  @RunWith(Parameterized.class)
  public class Real3DTest extends FFXTest {
  
    private final String info;
    private final int nx;
    private final int ny;
    private final int nz;
    private final int tot;
    private final double[] data;
    private final double[] expected;
    private final double[] recip;
    private final double tolerance = 1.0e-14;
  
    public Real3DTest(String info, int nx, int ny, int nz) {
      this.info = info;
      this.nx = nx;
      this.ny = ny;
      this.nz = nz;
      int paddedTot = (nx + 2) * ny * nz;
      tot = nx * ny * nz;
      data = new double[paddedTot];
      expected = new double[tot];
      recip = new double[tot];
    }
  
    @Parameters
    public static Collection<Object[]> data() {
      return Arrays.asList(
          new Object[][] {
            {"Test nx=32, ny=32, nz=32}", 32, 32, 32}, {"Test nx=32, ny=45, nz=21}", 32, 45, 21}
          });
    }
  
    @Before
    public void setUp() {
      Random random = new Random();
      int paddedIndex = 0;
      int index = 0;
      for (int z = 0; z < nz; z++) {
        for (int y = 0; y < ny; y++) {
          for (int x = 0; x < nx; x++) {
            double r = random.nextDouble();
            data[paddedIndex++] = r;
            expected[index] = r;
            recip[index++] = 1.0e0;
          }
         paddedIndex += 2;
       }
     }
   }
 
   /** Test of convolution method, of class Real3D. */
   @Test
   public void testConvolution() {
     Real3D real3D = new Real3D(nx, ny, nz);
     real3D.setRecip(recip);
     real3D.convolution(data);
     int paddedIndex = 0;
     int index = 0;
     for (int z = 0; z < nz; z++) {
       for (int y = 0; y < ny; y++) {
         for (int x = 0; x < nx; x++) {
           double actual = data[paddedIndex++] / tot;
           double orig = expected[index++];
           assertEquals(info, orig, actual, tolerance);
         }
         paddedIndex += 2;
       }
     }
   }
 
   /** Test of the fft and ifft methods, of class Real3D. */
   @Test
   public void testFft() {
     Real3D real3D = new Real3D(nx, ny, nz);
     real3D.fft(data);
     real3D.ifft(data);
     int paddedIndex = 0;
     int index = 0;
     for (int z = 0; z < nz; z++) {
       for (int y = 0; y < ny; y++) {
         for (int x = 0; x < nx; x++) {
           double actual = data[paddedIndex++] / tot;
           double orig = expected[index++];
           assertEquals(info, orig, actual, tolerance);
         }
         paddedIndex += 2;
       }
     }
   }
 }