GoldenSectionLineSearchTest.java

package edu.stanford.nlp.optimization;

import java.util.function.Function;
import junit.framework.TestCase;

public class GoldenSectionLineSearchTest extends TestCase {
    public void testEasy() {
      GoldenSectionLineSearch min = new GoldenSectionLineSearch(false, 0.00001, 0.0, 1.0, false);
      Function<Double,Double> f2 = new Function<Double,Double>() {
        public Double apply(Double x) {
          // this function used to fail in Galen's version; min should be 0.2
          // return - x * (2 * x - 1) * (x - 0.8);
          // this function fails if you don't find an initial bracketing
          return x < 0.1 ? 0.0: (x > 0.2 ? 0.0: (x - 0.1) * (x - 0.2));
          // return - Math.sin(x * Math.PI);
          // return -(3 + 6 * x - 4 * x * x);
        }
      };
      assertEquals(0.15,min.minimize(f2),1E-4);
    }
}