/****************************************************************************
Copyright (c) 2004, Colorado School of Mines and others. All rights reserved.
This program and accompanying materials are made available under the terms of
the Common Public License - v1.0, which accompanies this distribution, and is
available at http://www.eclipse.org/legal/cpl-v10.html
****************************************************************************/
package edu.mines.jtk.opt.test;

import junit.framework.TestCase;
import junit.framework.TestSuite;

import edu.mines.jtk.opt.BrentMinFinder;
import static edu.mines.jtk.util.MathPlus.*;

/**
 * Tests {@link edu.mines.jtk.util.BrentMinFinder}.
 * @author Dave Hale, Colorado School of Mines
 * @version 2004.09.15, 2006.08.14
 */
public class BrentMinFinderTest extends TestCase {
  public static void main(String[] args) {
    TestSuite suite = new TestSuite(BrentMinFinderTest.class);
    junit.textui.TestRunner.run(suite);
  }

  public void testSimple() {
    BrentMinFinder bmf = new BrentMinFinder(new BrentMinFinder.Function() {
      public double evaluate(double x) {
        return x*(x*x-2.0)-5.0;
      }
    });
    double xmin = bmf.findMin(0.0,1.0,1.0e-5);
    trace("xmin="+xmin);
    assertEquals(0.81650,xmin,0.00001);
  }
  
  private void trace(String s) {
    //System.out.println(s);
  }
  
  // Test functions with results published by Forsythe et al.
  abstract class BrentTestFunc implements BrentMinFinder.Function {
    void findMin(double a, double b) {
      _count = 0;
      BrentMinFinder minFinder = new BrentMinFinder(this);
      double xmin = minFinder.findMin(a,b,DBL_EPSILON);
      double ymin = eval(xmin);
      checkMin(xmin);
      checkFunc(ymin);
      checkCount(_count);
    }
    public double evaluate(double x) {
      ++_count;
      return eval(x);
    }
    abstract double eval(double x);
    abstract void checkMin(double x);
    abstract void checkFunc(double y);
    abstract void checkCount(int count);
    private int _count;
  }
  class MinFunc1 extends BrentTestFunc {
    double eval(double x) {
      return (pow(x,2)-2.0)*x-5.0;
    }
    void checkMin(double x) {
      assertEqual(x,8.164965811e-01);
    }
    void checkFunc(double y) {
      assertEqual(y,-6.0887e+00);
    }
    void checkCount(int count) {
      assertEqual(count,11);
    }
  }
  class MinFunc2 extends BrentTestFunc {
    double eval(double x) {
      return pow((pow(x,2)-2.0)*x-5.0,2);
    }
    void checkMin(double x) {
      assertEqual(x,2.094551483e+00);
    }
    void checkFunc(double y) {
      assertEqual(y,2.7186e-16);
    }
    void checkCount(int count) {
      assertEqual(count,13);
    }
  }
  class MinFunc3 extends BrentTestFunc {
    double eval(double x) {
      return pow(cos(x)-x,2)-2;
    }
    void checkMin(double x) {
      assertEqual(x,7.390851269e-01);
    }
    void checkFunc(double y) {
      assertEqual(y,-2.0);
    }
    void checkCount(int count) {
      assertEqual(count,13);
    }
  }
  class MinFunc4 extends BrentTestFunc {
    double eval(double x) {
      return pow(sin(x)-x,2)+1;
    }
    void checkMin(double x) {
      assertEqual(x,-3.125827630e-04);
    }
    void checkFunc(double y) {
      assertEqual(y,1.0);
    }
    void checkCount(int count) {
      assertEqual(count,47);
    }
  }

  public void testMinFinder() {
    MinFunc1 f1 = new MinFunc1();
    f1.findMin(0.0,1.0);
    MinFunc2 f2 = new MinFunc2();
    f2.findMin(2.0,3.0);
    MinFunc3 f3 = new MinFunc3();
    f3.findMin(-1.0,3.0);
    MinFunc4 f4 = new MinFunc4();
    f4.findMin(-1.0,3.0);
  }

  private static void assertEqual(double x, double y) {
    assertTrue(x+" = "+y,almostEqual(x,y));
  }
  
  private static boolean almostEqual(double x, double y) {
    double ax = abs(x);
    double ay = abs(y);
    return abs(x-y)<=0.0001*max(ax,ay);
  }
}