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    * CS licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *   http://www.apache.org/licenses/LICENSE-2.0
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   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
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   * See the License for the specific language governing permissions and
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  package org.orekit.time;
  
  
  import org.junit.Assert;
  import org.junit.Before;
  import org.junit.Test;
  import org.orekit.Utils;
  import org.orekit.frames.ITRFVersion;
  import org.orekit.utils.Constants;
  import org.orekit.utils.IERSConventions;
  
  
  public class TCGScaleTest {
  
      @Test
      public void testRatio() {
          TimeScale scale = TimeScalesFactory.getTCG();
          Assert.assertEquals("TCG", scale.toString());
          final double dtTT = 1e6;
          final AbsoluteDate t1 = AbsoluteDate.J2000_EPOCH;
          final AbsoluteDate t2 = t1.shiftedBy(dtTT);
          final double dtTCG = dtTT + scale.offsetFromTAI(t2) - scale.offsetFromTAI(t1);
          Assert.assertEquals(1 - 6.969290134e-10, dtTT / dtTCG, 1.0e-15);
      }
  
      @Test
      public void testSymmetry() {
          TimeScale scale = TimeScalesFactory.getTCG();
          for (double dt = -10000; dt < 10000; dt += 123.456789) {
              AbsoluteDate date = AbsoluteDate.J2000_EPOCH.shiftedBy(dt * Constants.JULIAN_DAY);
              double dt1 = scale.offsetFromTAI(date);
              DateTimeComponents components = date.getComponents(scale);
              double dt2 = scale.offsetToTAI(components.getDate(), components.getTime());
              Assert.assertEquals( 0.0, dt1 + dt2, 1.0e-10);
          }
      }
  
      @Test
      public void testDuringLeap() {
          final TimeScale utc   = TimeScalesFactory.getUTC();
          final TimeScale scale = TimeScalesFactory.getTCG();
          final AbsoluteDate before = new AbsoluteDate(new DateComponents(1983, 06, 30),
                                                       new TimeComponents(23, 59, 59),
                                                       utc);
          final AbsoluteDate during = before.shiftedBy(1.25);
          Assert.assertEquals(61, utc.minuteDuration(during));
          Assert.assertEquals(1.0, utc.getLeap(during), 1.0e-10);
          Assert.assertEquals(60, scale.minuteDuration(during));
          Assert.assertEquals(0.0, scale.getLeap(during), 1.0e-10);
      }
  
      @Test
      public void testReference() {
          DateComponents  referenceDate = new DateComponents(1977, 01, 01);
          TimeComponents  thirtyTwo     = new TimeComponents(0, 0, 32.184);
          AbsoluteDate ttRef         = new AbsoluteDate(referenceDate, thirtyTwo, TimeScalesFactory.getTT());
          AbsoluteDate tcgRef        = new AbsoluteDate(referenceDate, thirtyTwo, TimeScalesFactory.getTCG());
          AbsoluteDate taiRef        = new AbsoluteDate(referenceDate, TimeComponents.H00, TimeScalesFactory.getTAI());
          AbsoluteDate utcRef        = new AbsoluteDate(new DateComponents(1976, 12, 31),
                                                        new TimeComponents(23, 59, 45),
                                                        TimeScalesFactory.getUTC());
          Assert.assertEquals(0, ttRef.durationFrom(tcgRef), 1.0e-15);
          Assert.assertEquals(0, ttRef.durationFrom(taiRef), 1.0e-15);
          Assert.assertEquals(0, ttRef.durationFrom(utcRef), 1.0e-15);
      }
  
      @Test
      public void testSofa() {
          TimeScale tt  = TimeScalesFactory.getTT();
          AbsoluteDate date = new AbsoluteDate(2006, 1, 15, 21, 25, 10.5000096, tt);
          double delta = TimeScalesFactory.getTCG().offsetFromTAI(date) - tt.offsetFromTAI(date);
          Assert.assertEquals(Constants.JULIAN_DAY * (0.8924900312508587113 -  0.892482639), delta, 5.0e-10);
      }
  
      @Test
      public void testAAS06134() {
  
          // this reference test has been extracted from the following paper:
          // Implementation Issues Surrounding the New IAU Reference Systems for Astrodynamics
          // David A. Vallado, John H. Seago, P. Kenneth Seidelmann
          // http://www.centerforspace.com/downloads/files/pubs/AAS-06-134.pdf
          // Note that the dUT1 here is -0.439962, whereas it is -0.4399619 in the book
          Utils.setLoaders(IERSConventions.IERS_1996,
                          Utils.buildEOPList(IERSConventions.IERS_1996, ITRFVersion.ITRF_2008, new double[][] {
                              { 53098, -0.439962, 0.0015563, -0.140682, 0.333309, -0.052195, -0.003875, Double.NaN, Double.NaN },
                              { 53099, -0.439962, 0.0015563, -0.140682, 0.333309, -0.052195, -0.003875, Double.NaN, Double.NaN },
                              { 53100, -0.439962, 0.0015563, -0.140682, 0.333309, -0.052195, -0.003875, Double.NaN, Double.NaN },
                              { 53101, -0.439962, 0.0015563, -0.140682, 0.333309, -0.052195, -0.003875, Double.NaN, Double.NaN },
                              { 53102, -0.439962, 0.0015563, -0.140682, 0.333309, -0.052195, -0.003875, Double.NaN, Double.NaN },
                              { 53103, -0.439962, 0.0015563, -0.140682, 0.333309, -0.052195, -0.003875, Double.NaN, Double.NaN },
                              { 53104, -0.439962, 0.0015563, -0.140682, 0.333309, -0.052195, -0.003875, Double.NaN, Double.NaN },
                              { 53105, -0.439962, 0.0015563, -0.140682, 0.333309, -0.052195, -0.003875, Double.NaN, Double.NaN }
                          }));
         AbsoluteDate date =
                 new AbsoluteDate(2004, 4, 6, 7, 51, 28.386009, TimeScalesFactory.getUTC());
         DateTimeComponents components = date.getComponents(TimeScalesFactory.getTCG());
         Assert.assertEquals(2004,            components.getDate().getYear());
         Assert.assertEquals(   4,            components.getDate().getMonth());
         Assert.assertEquals(   6,            components.getDate().getDay());
         Assert.assertEquals(   7,            components.getTime().getHour());
         Assert.assertEquals(  52,            components.getTime().getMinute());
         Assert.assertEquals(  33.1695861742, components.getTime().getSecond(), 1.0e-10);
 
     }
 
     @Before
     public void setUp() {
         Utils.setDataRoot("regular-data");
     }
 
 }