/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF 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
    *
    *      https://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  /*
   * This is not the original file distributed by the Apache Software Foundation
   * It has been modified by the Hipparchus project
   */
  package org.hipparchus.optim.univariate;
  
  import org.hipparchus.analysis.QuinticFunction;
  import org.hipparchus.analysis.UnivariateFunction;
  import org.hipparchus.analysis.function.Sin;
  import org.hipparchus.exception.MathIllegalStateException;
  import org.hipparchus.optim.MaxEval;
  import org.hipparchus.optim.nonlinear.scalar.GoalType;
  import org.hipparchus.random.JDKRandomGenerator;
  import org.hipparchus.util.FastMath;
  import org.junit.Assert;
  import org.junit.Test;
  
  public class MultiStartUnivariateOptimizerTest {
      @Test(expected=MathIllegalStateException.class)
      public void testMissingMaxEval() {
          UnivariateOptimizer underlying = new BrentOptimizer(1e-10, 1e-14);
          JDKRandomGenerator g = new JDKRandomGenerator();
          g.setSeed(44428400075l);
          MultiStartUnivariateOptimizer optimizer = new MultiStartUnivariateOptimizer(underlying, 10, g);
          optimizer.optimize(new UnivariateObjectiveFunction(new Sin()),
                             GoalType.MINIMIZE,
                             new SearchInterval(-1, 1));
      }
      @Test(expected=MathIllegalStateException.class)
      public void testMissingSearchInterval() {
          UnivariateOptimizer underlying = new BrentOptimizer(1e-10, 1e-14);
          JDKRandomGenerator g = new JDKRandomGenerator();
          g.setSeed(44428400075l);
          MultiStartUnivariateOptimizer optimizer = new MultiStartUnivariateOptimizer(underlying, 10, g);
          optimizer.optimize(new MaxEval(300),
                             new UnivariateObjectiveFunction(new Sin()),
                             GoalType.MINIMIZE);
      }
  
      @Test
      public void testSinMin() {
          UnivariateFunction f = new Sin();
          UnivariateOptimizer underlying = new BrentOptimizer(1e-10, 1e-14);
          JDKRandomGenerator g = new JDKRandomGenerator();
          g.setSeed(44428400075l);
          MultiStartUnivariateOptimizer optimizer = new MultiStartUnivariateOptimizer(underlying, 10, g);
          optimizer.optimize(new MaxEval(300),
                             new UnivariateObjectiveFunction(f),
                             GoalType.MINIMIZE,
                             new SearchInterval(-100.0, 100.0));
          UnivariatePointValuePair[] optima = optimizer.getOptima();
          for (int i = 1; i < optima.length; ++i) {
              double d = (optima[i].getPoint() - optima[i-1].getPoint()) / (2 * FastMath.PI);
              Assert.assertTrue(FastMath.abs(d - FastMath.rint(d)) < 1.0e-8);
              Assert.assertEquals(-1.0, f.value(optima[i].getPoint()), 1.0e-10);
              Assert.assertEquals(f.value(optima[i].getPoint()), optima[i].getValue(), 1.0e-10);
          }
          Assert.assertTrue(optimizer.getEvaluations() > 200);
          Assert.assertTrue(optimizer.getEvaluations() < 300);
      }
  
      @Test
      public void testQuinticMin() {
          // The quintic function has zeros at 0, +-0.5 and +-1.
          // The function has extrema (first derivative is zero) at 0.27195613 and 0.82221643,
          UnivariateFunction f = new QuinticFunction();
          UnivariateOptimizer underlying = new BrentOptimizer(1e-9, 1e-14);
          JDKRandomGenerator g = new JDKRandomGenerator();
          g.setSeed(4312000053L);
          MultiStartUnivariateOptimizer optimizer = new MultiStartUnivariateOptimizer(underlying, 5, g);
  
          UnivariatePointValuePair optimum
              = optimizer.optimize(new MaxEval(300),
                                   new UnivariateObjectiveFunction(f),
                                   GoalType.MINIMIZE,
                                   new SearchInterval(-0.3, -0.2));
          Assert.assertEquals(-0.27195613, optimum.getPoint(), 1e-9);
          Assert.assertEquals(-0.0443342695, optimum.getValue(), 1e-9);
  
          UnivariatePointValuePair[] optima = optimizer.getOptima();
          for (int i = 0; i < optima.length; ++i) {
              Assert.assertEquals(f.value(optima[i].getPoint()), optima[i].getValue(), 1e-9);
         }
         Assert.assertTrue(optimizer.getEvaluations() >= 50);
         Assert.assertTrue(optimizer.getEvaluations() <= 100);
     }
 
     @Test
     public void testBadFunction() {
         UnivariateFunction f = new UnivariateFunction() {
                 public double value(double x) {
                     if (x < 0) {
                         throw new LocalException();
                     }
                     return 0;
                 }
             };
         UnivariateOptimizer underlying = new BrentOptimizer(1e-9, 1e-14);
         JDKRandomGenerator g = new JDKRandomGenerator();
         g.setSeed(4312000053L);
         MultiStartUnivariateOptimizer optimizer = new MultiStartUnivariateOptimizer(underlying, 5, g);
 
         try {
             optimizer.optimize(new MaxEval(300),
                                new UnivariateObjectiveFunction(f),
                                GoalType.MINIMIZE,
                                new SearchInterval(-0.3, -0.2));
             Assert.fail();
         } catch (LocalException e) {
             // Expected.
         }
 
         // Ensure that the exception was thrown because no optimum was found.
         Assert.assertTrue(optimizer.getOptima()[0] == null);
     }
 
     private static class LocalException extends RuntimeException {
         private static final long serialVersionUID = 1194682757034350629L;
     }
 
 }