cvs commit: jakarta-commons/math/src/test/org/apache/commons/math/analysis PolynomialSplineFunctionTest.java

[ps...@apache.org]

psteitz     2004/07/20 05:57:22

  Added:       math/src/test/org/apache/commons/math/analysis
                        PolynomialSplineFunctionTest.java
  Log:
  Added test class for PolynomialSplineFunction.
  
  Revision  Changes    Path
  1.1                  jakarta-commons/math/src/test/org/apache/commons/math/analysis/PolynomialSplineFunctionTest.java
  
  Index: PolynomialSplineFunctionTest.java
  ===================================================================
  /*
   * 
   * Copyright (c) 2004 The Apache Software Foundation. All rights reserved.
   * 
   * Licensed 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
   * 
   * 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.
   *  
   */
  package org.apache.commons.math.analysis;
  
  import java.util.Arrays;
  import junit.framework.TestCase;
  
  import org.apache.commons.math.FunctionEvaluationException;
  
  /**
   * Tests the PolynomialSplineFunction implementation.
   *
   * @version $Revision: 1.1 $
   */
  public class PolynomialSplineFunctionTest extends TestCase {
  
      /** Error tolerance for tests */
      protected double tolerance = 1.0e-12;
      
      /** 
       * Quadratic polynomials used in tests: 
       * 
       * x^2 + x            [-1, 0)
       * x^2 + x + 2        [0, 1)
       * x^2 + x + 4        [1, 2)
       * 
       * Defined so that evaluation using PolynomialSplineFunction evaluation
       * algorithm agrees at knot point boundaries.
       */
      protected PolynomialFunction[] polynomials = {
          new PolynomialFunction(new double[] {0d, 1d, 1d}), 
          new PolynomialFunction(new double[] {2d, 1d, 1d}),
          new PolynomialFunction(new double[] {4d, 1d, 1d})
      };
      
      /** Knot points  */
      protected double[] knots = {-1, 0, 1, 2};
      
      /** Derivative of test polynomials -- 2x + 1  */
      protected PolynomialFunction dp = 
          new PolynomialFunction(new double[] {1d, 2d});
      
      
      public void testConstructor() {
          PolynomialSplineFunction spline = 
              new PolynomialSplineFunction(knots, polynomials);
          assertTrue(Arrays.equals(knots, spline.getKnots()));
          assertEquals(1d, spline.getPolynomials()[0].getCoefficients()[2], 0);
          
          try { // too few knots
              spline = 
                  new PolynomialSplineFunction(new double[] {0}, polynomials);
              fail("Expecting IllegalArgumentException");
          } catch (IllegalArgumentException ex) {
              // expected
          }
          
          try { // too many knots
              spline = 
                  new PolynomialSplineFunction(new double[] {0,1,2,3,4}, polynomials);
              fail("Expecting IllegalArgumentException");
          } catch (IllegalArgumentException ex) {
              // expected
          }
          
          try { // knots not increasing
              spline = 
                  new PolynomialSplineFunction(new double[] {0,1, 3, 2}, polynomials);
              fail("Expecting IllegalArgumentException");
          } catch (IllegalArgumentException ex) {
              // expected
          }
      }
      
      public void testValues() throws Exception {
          PolynomialSplineFunction spline = 
              new PolynomialSplineFunction(knots, polynomials);
          UnivariateRealFunction dSpline = spline.derivative();
          
          /**
           * interior points -- spline value at x should equal p(x - knot)
           * where knot is the largest knot point less than or equal to x and p 
           * is the polynomial defined over the knot segment to which x belongs.
           */
          double x = -1;
          int index = 0;
          for (int i = 0; i < 10; i++) {
             x+=0.25;
             index = findKnot(knots, x);
             assertEquals("spline function evaluation failed for x=" + x, 
                     polynomials[index].value(x - knots[index]), spline.value(x), tolerance);
             assertEquals("spline derivative evaluation failed for x=" + x,
                     dp.value(x - knots[index]), dSpline.value(x), tolerance);
          }
          
          // knot points -- centering should zero arguments
          for (int i = 0; i < 3; i++) {
              assertEquals("spline function evaluation failed for knot=" + knots[i],
                      polynomials[i].value(0), spline.value(knots[i]), tolerance);
              assertEquals("spline function evaluation failed for knot=" + knots[i],
                      dp.value(0), dSpline.value(knots[i]), tolerance);
          }
          
          try { //outside of domain -- under min
              x = spline.value(-1.5);
              fail("Expecting IllegalArgumentException");
          } catch (FunctionEvaluationException ex) {
              // expected
          }
          
          try { //outside of domain -- over max
              x = spline.value(2.5);
              fail("Expecting IllegalArgumentException");
          } catch (FunctionEvaluationException ex) {
              // expected
          }         
      }  
      
      /**
       *  Do linear search to find largest knot point less than or equal to x.
       *  Implementation does binary search.
       */
       protected int findKnot(double[] knots, double x) {
           if (x < knots[0] || x >= knots[knots.length -1]) {
               throw new IllegalArgumentException("x is out of range");
           }
           for (int i = 0; i < knots.length; i++) {
               if (knots[i] > x) {
                   return i -1;
               }
           }
           throw new IllegalArgumentException("x is out of range");
       }
  }
      
  
  
  

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