mdiggory    2003/11/10 09:34:03

  Modified:    math/src/test/org/apache/commons/math/analysis
                        SinFunction.java InterpolatorTest.java
                        QuinticFunction.java
               math/src/java/org/apache/commons/math/analysis
                        CubicSplineFunction.java
                        UnivariateRealFunction.java
  Added:       math/src/test/org/apache/commons/math/analysis
                        PolynomialFunctionTest.java
               math/src/java/org/apache/commons/math/analysis
                        PolynomialFunction.java
  Log:
  PR: http://www.mail-archive.com/[EMAIL PROTECTED]/msg29959.html
  Submitted by: Matt Cliff
  Reviewed by:  Mark Diggory
  
  Revision  Changes    Path
  1.2       +1 -10     
jakarta-commons/math/src/test/org/apache/commons/math/analysis/SinFunction.java
  
  Index: SinFunction.java
  ===================================================================
  RCS file: 
/home/cvs/jakarta-commons/math/src/test/org/apache/commons/math/analysis/SinFunction.java,v
  retrieving revision 1.1
  retrieving revision 1.2
  diff -u -r1.1 -r1.2
  --- SinFunction.java  1 Nov 2003 16:04:12 -0000       1.1
  +++ SinFunction.java  10 Nov 2003 17:34:03 -0000      1.2
  @@ -75,18 +75,9 @@
       }
   
       /* First derivative of sinus function
  -     * @see org.apache.commons.math.UnivariateRealFunction#firstDerivative(double)
        */
       public double firstDerivative(double x) throws MathException {
           return Math.cos(x);
  -    }
  -
  -    /* Second derivative of sinus function.
  -     * Unsupported.
  -     * @see org.apache.commons.math.UnivariateRealFunction#secondDerivative(double)
  -     */
  -    public double secondDerivative(double x) throws MathException {
  -        throw new UnsupportedOperationException();
       }
   
   }
  
  
  
  1.2       +41 -106   
jakarta-commons/math/src/test/org/apache/commons/math/analysis/InterpolatorTest.java
  
  Index: InterpolatorTest.java
  ===================================================================
  RCS file: 
/home/cvs/jakarta-commons/math/src/test/org/apache/commons/math/analysis/InterpolatorTest.java,v
  retrieving revision 1.1
  retrieving revision 1.2
  diff -u -r1.1 -r1.2
  --- InterpolatorTest.java     1 Nov 2003 16:04:12 -0000       1.1
  +++ InterpolatorTest.java     10 Nov 2003 17:34:03 -0000      1.2
  @@ -89,31 +89,21 @@
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
           x = 0.5;
           System.out.println(
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
           x = 1 - 1E-6;
           System.out.println(
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
       }
   
       public void testInterpolateLinearDegenerateThreeSegment()
  @@ -129,61 +119,43 @@
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
           x = 0.5 - 1E-6;
           System.out.println(
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
           x = 0.5;
           System.out.println(
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
           x = 1 - 1E-6;
           System.out.println(
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
           x = 1;
           System.out.println(
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
           x = 1.5 - 1E-6;
           System.out.println(
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
       }
   
       public void testInterpolateLinear() throws MathException {
  @@ -198,41 +170,28 @@
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
           x = 0.5 - 1E-6;
           System.out.println(
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
           x = 0.5;
           System.out.println(
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
           x = 1 - 1E-6;
           System.out.println(
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
       }
   
       public void testInterpolateSin() throws MathException {
  @@ -259,81 +218,57 @@
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
           x = Math.PI / 6.0 - 1E-6;
           System.out.println(
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
           x = Math.PI / 6.0 + 1E-6;
           System.out.println(
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
           x = Math.PI / 2 - 1E-6;
           System.out.println(
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
           x = Math.PI / 2 + 1E-6;
           System.out.println(
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
           x = Math.PI - 1E-6;
           System.out.println(
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
           x = Math.PI + 1E-6;
           System.out.println(
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
           x = 2.0 * Math.PI - 1E-6;
           System.out.println(
               "x="
                   + x
                   + " y="
  -                + f.value(x)
  -                + " y'="
  -                + f.firstDerivative(x)
  -                + " y''="
  -                + f.secondDerivative(x));
  +                + f.value(x));
  +
           //assertEquals(0.5,f.value(Math.PI/6.0),)
       }
   
  
  
  
  1.2       +1 -10     
jakarta-commons/math/src/test/org/apache/commons/math/analysis/QuinticFunction.java
  
  Index: QuinticFunction.java
  ===================================================================
  RCS file: 
/home/cvs/jakarta-commons/math/src/test/org/apache/commons/math/analysis/QuinticFunction.java,v
  retrieving revision 1.1
  retrieving revision 1.2
  diff -u -r1.1 -r1.2
  --- QuinticFunction.java      1 Nov 2003 16:04:12 -0000       1.1
  +++ QuinticFunction.java      10 Nov 2003 17:34:03 -0000      1.2
  @@ -70,18 +70,9 @@
       }
   
       /* First derivative of quintic.
  -     * @see org.apache.commons.math.UnivariateRealFunction#firstDerivative(double)
        */
       public double firstDerivative(double x) throws MathException {
           return (5*x*x-3.75)*x*x+0.25;
  -    }
  -
  -    /* Second order derivative of quintic.
  -     * Unsupported.
  -     * @see org.apache.commons.math.UnivariateRealFunction#secondDerivative(double)
  -     */
  -    public double secondDerivative(double x) throws MathException {
  -        throw new UnsupportedOperationException();
       }
   
   }
  
  
  
  1.1                  
jakarta-commons/math/src/test/org/apache/commons/math/analysis/PolynomialFunctionTest.java
  
  Index: PolynomialFunctionTest.java
  ===================================================================
  /* ====================================================================
   * The Apache Software License, Version 1.1
   *
   * Copyright (c) 2003 The Apache Software Foundation.  All rights
   * reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. The end-user documentation included with the redistribution, if
   *    any, must include the following acknowledgement:
   *       "This product includes software developed by the
   *        Apache Software Foundation (http://www.apache.org/)."
   *    Alternately, this acknowledgement may appear in the software itself,
   *    if and wherever such third-party acknowledgements normally appear.
   *
   * 4. The names "The Jakarta Project", "Commons", and "Apache Software
   *    Foundation" must not be used to endorse or promote products derived
   *    from this software without prior written permission. For written
   *    permission, please contact [EMAIL PROTECTED]
   *
   * 5. Products derived from this software may not be called "Apache"
   *    nor may "Apache" appear in their name without prior written
   *    permission of the Apache Software Foundation.
   *
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   */
  package org.apache.commons.math.analysis;
  
  // commons-math
  import org.apache.commons.math.MathException;
  
  // junit
  import junit.framework.TestCase;
  
  /**
   * Tests the PolynomialFunction implementation of a UnivariateRealFunction.
   *
   * @version $Revision: 1.1 $
   * @author Matt Cliff <[EMAIL PROTECTED]>
   */
  public final class PolynomialFunctionTest extends TestCase {
  
      // all values are known precisely accept 15 digit precision error 
      final double error = 1.0e-15;
  
      /**
       * tests the value of a constant polynomial.
       *
       * <p>value of this is 2.5 everywhere.</p>
       */
      public void testConstants() throws MathException {
          double[] c = { 2.5 };
          UnivariateRealFunction f = new PolynomialFunction( c );
  
          // verify that we are equal to c[0] at several (nonsymmetric) places
          assertEquals( f.value( 0.0), c[0], error );
          assertEquals( f.value( -1.0), c[0], error );
          assertEquals( f.value( -123.5), c[0], error );
          assertEquals( f.value( 3.0), c[0], error );
          assertEquals( f.value( 456.89), c[0], error );
      }
  
  
  
      /**
       * tests the value of a linear polynomial.
       *
       * <p>This will test the function f(x) = 3*x - 1.5</p>
       * <p>This will have the values 
       *  <tt>f(0.0) = -1.5, f(-1.0) = -4.5, f(-2.5) = -9.0,
       *      f(0.5) = 0.0, f(1.5) = 3.0</tt> and <tt>f(3.0) = 7.5</tt>
       * </p>
       */
      public void testLinear() throws MathException {
          double[] c = { -1.5, 3.0 };
          UnivariateRealFunction f = new PolynomialFunction( c );
  
          // verify that we are equal to c[0] when x=0
          assertEquals( f.value( 0.0), c[0], error );
  
          // now check a few other places
          assertEquals( -4.5, f.value( -1.0), error );
          assertEquals( -9.0, f.value( -2.5), error );
          assertEquals( 0.0, f.value( 0.5), error );
          assertEquals( 3.0, f.value( 1.5), error );
          assertEquals( 7.5, f.value( 3.0), error );
      
      }
  
  
      /**
       * Tests a second order polynomial.
       * <p> This will test the function f(x) = 2x^2 - 3x -2 = (2x+1)(x-2)</p>
       *
       */
      public void testQuadratic() throws MathException {
          double[] c = { -2.0, -3.0, 2.0 };
          UnivariateRealFunction f = new PolynomialFunction( c );
  
          // verify that we are equal to c[0] when x=0
          assertEquals( f.value( 0.0), c[0], error );
  
          // now check a few other places
          assertEquals( 0.0, f.value( -0.5), error );
          assertEquals( 0.0, f.value( 2.0), error );
          assertEquals( -2.0, f.value( 1.5), error );
          assertEquals( 7.0, f.value( -1.5), error );
          assertEquals( 265.5312, f.value( 12.34), error );
      
      }    
  
  
      /** 
       * This will test the quintic function 
       *   f(x) = x^2(x-5)(x+3)(x-1) = x^5 - 3x^4 -13x^3 + 15x^2</p>
       *
       */
      public void testQuintic() throws MathException {
          double[] c = { 0.0, 0.0, 15.0, -13.0, -3.0, 1.0 };
          UnivariateRealFunction f = new PolynomialFunction( c );
  
          // verify that we are equal to c[0] when x=0
          assertEquals( f.value( 0.0), c[0], error );
  
          // now check a few other places
          assertEquals( 0.0, f.value( 5.0), error );
          assertEquals( 0.0, f.value( 1.0), error );
          assertEquals( 0.0, f.value( -3.0), error );
          assertEquals( 54.84375, f.value( -1.5), error );
          assertEquals( -8.06637, f.value( 1.3), error );
      
      }    
  
  
      /**
       * tests the derivative function by comparision
       *
       * <p>This will test the functions 
       * <tt>f(x) = x^3 - 2x^2 + 6x + 3, g(x) = 3x^2 - 4x + 6</tt>
       * and <tt>h(x) = 6x - 4</tt>
       */
      public void testDerivativeComparision() throws MathException {
          double[] f_coeff = { 3.0, 6.0, -2.0, 1.0 };
          double[] g_coeff = { 6.0, -4.0, 3.0 };
          double[] h_coeff = { -4.0, 6.0 };
  
          PolynomialFunction f = new PolynomialFunction( f_coeff );
          PolynomialFunction g = new PolynomialFunction( g_coeff );
          PolynomialFunction h = new PolynomialFunction( h_coeff );
  
          // compare f' = g
          assertEquals( f.firstDerivative(0.0), g.value(0.0), error );
          assertEquals( f.firstDerivative(1.0), g.value(1.0), error );
          assertEquals( f.firstDerivative(100.0), g.value(100.0), error );
          assertEquals( f.firstDerivative(4.1), g.value(4.1), error );
          assertEquals( f.firstDerivative(-3.25), g.value(-3.25), error );
  
          // compare g' = h
  
  
          // compare f'' = h
      }
  
  
  
  
  
  }
  
  
  
  1.2       +1 -3      
jakarta-commons/math/src/java/org/apache/commons/math/analysis/CubicSplineFunction.java
  
  Index: CubicSplineFunction.java
  ===================================================================
  RCS file: 
/home/cvs/jakarta-commons/math/src/java/org/apache/commons/math/analysis/CubicSplineFunction.java,v
  retrieving revision 1.1
  retrieving revision 1.2
  diff -u -r1.1 -r1.2
  --- CubicSplineFunction.java  1 Nov 2003 16:04:12 -0000       1.1
  +++ CubicSplineFunction.java  10 Nov 2003 17:34:03 -0000      1.2
  @@ -122,7 +122,6 @@
        * @param x the point for which the first derivative should be computed
        * @return the value
        * @throws MathException if the derivative couldn't be computed.
  -     * @see UnivariateRealFunction#firstDerivative(double)
        */
       public double firstDerivative(double x) throws MathException {
           if (x < xval[0] || x > xval[xval.length - 1]) {
  @@ -145,7 +144,6 @@
        * @param x the point for which the first derivative should be computed
        * @return the value
        * @throws MathException if the second derivative couldn't be computed.
  -     * @see UnivariateRealFunction#secondDerivative(double)
        */
       public double secondDerivative(double x) throws MathException {
           if (x < xval[0] || x > xval[xval.length - 1]) {
  
  
  
  1.2       +1 -24     
jakarta-commons/math/src/java/org/apache/commons/math/analysis/UnivariateRealFunction.java
  
  Index: UnivariateRealFunction.java
  ===================================================================
  RCS file: 
/home/cvs/jakarta-commons/math/src/java/org/apache/commons/math/analysis/UnivariateRealFunction.java,v
  retrieving revision 1.1
  retrieving revision 1.2
  diff -u -r1.1 -r1.2
  --- UnivariateRealFunction.java       1 Nov 2003 16:04:12 -0000       1.1
  +++ UnivariateRealFunction.java       10 Nov 2003 17:34:03 -0000      1.2
  @@ -74,27 +74,4 @@
        */
       public double value(double x) throws MathException;
   
  -    /**
  -     * Compute the value for the first derivative of the function.
  -     * It is recommended to provide this method only if the first derivative is
  -     * analytical. Numerical derivatives may be acceptable in some cases.
  -     * An implementation should throw an UnsupportedOperationException if
  -     * this method is not implemented.
  -     * @param x the point for which the first derivative should be computed
  -     * @return the value
  -     * @throws MathException if the derivative couldn't be computed.
  -     */
  -    public double firstDerivative(double x) throws MathException;
  -
  -    /**
  -     * Compute the value for the second derivative of the function.
  -     * It is recommended to provide this method only if the second derivative is
  -     * analytical. Numerical derivatives may be acceptable in some cases.
  -     * An implementation should throw an UnsupportedOperationException if
  -     * this method is not implemented.
  -     * @param x the point for which the first derivative should be computed
  -     * @return the value
  -     * @throws MathException if the second derivative couldn't be computed.
  -     */
  -    public double secondDerivative(double x) throws MathException;
   }
  
  
  
  1.1                  
jakarta-commons/math/src/java/org/apache/commons/math/analysis/PolynomialFunction.java
  
  Index: PolynomialFunction.java
  ===================================================================
  /* ====================================================================
   * The Apache Software License, Version 1.1
   *
   * Copyright (c) 2003 The Apache Software Foundation.  All rights
   * reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. The end-user documentation included with the redistribution, if
   *    any, must include the following acknowledgement:
   *       "This product includes software developed by the
   *        Apache Software Foundation (http://www.apache.org/)."
   *    Alternately, this acknowledgement may appear in the software itself,
   *    if and wherever such third-party acknowledgements normally appear.
   *
   * 4. The names "The Jakarta Project", "Commons", and "Apache Software
   *    Foundation" must not be used to endorse or promote products derived
   *    from this software without prior written permission. For written
   *    permission, please contact [EMAIL PROTECTED]
   *
   * 5. Products derived from this software may not be called "Apache"
   *    nor may "Apache" appear in their name without prior written
   *    permission of the Apache Software Foundation.
   *
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   */
  package org.apache.commons.math.analysis;
  
  
  
  import org.apache.commons.math.MathException;
  
  /**
   * Represents a Polynomial function.
   * Spline functions map a certain interval of real numbers to real numbers.
   * A cubic spline consists of segments of cubic functions. For this class,
   * polynominal coefficents are used.
   * Arguments outside of the domain cause an IllegalArgumentException.
   * 
   * @version $Revision: 1.1 $ $Date: 2003/11/10 17:34:03 $
   */
  public class PolynomialFunction implements UnivariateRealFunction {
  
      /**
       * The polynominal coefficients.
       * The index represents the coefficients of the polynomail, with
       * index 0 being the absolute coefficient and index N the coefficient
       * for the Nth power.
       */
      private double c[];
  
      /**
       * Construct a function with the given segment delimiters and polynomial
       * coefficients.
       * @param c polynominal coefficients
       */
      public PolynomialFunction(double c[]) {
          super();
          // TODO: should copy the arguments here, for safety. This could be a major 
overhead.
          this.c = c;
      }
  
      /**
       * Compute the value for the function.
       *
       * <p>This can be explicitly determined by 
       *   <tt>c_n * x^n + ... + c_1 * x  + c_0</tt>
       * </p>
       *
       * @param x the point for which the function value should be computed
       * @return the value
       * @throws MathException if the function couldn't be computed due to
       *  missing additional data or other environmental problems.
       * @see UnivariateRealFunction#value(double)
       */
      public double value(double x) throws MathException {
  
          double value = c[0];
  
          for (int i=1; i < c.length; i++ ) {
              value += c[i] * Math.pow( x, (int)i);
          }
  
          return value;
      }
  
  
  
      /**
       * Compute the value for the first derivative of the function.
       *
       * <p>This can be explicitly determined by 
       *   <tt>n * c_n * x^(n-1) + ... + 2 * c_2 * x  + c_1</tt>
       * </p>
       *
       * @param x the point for which the first derivative should be computed
       * @return the value
       * @throws MathException if the derivative couldn't be computed.
       */
      public double firstDerivative(double x) throws MathException {
  
          double value = c[1];
  
          if ( c.length > 1 ) {
              for (int i=2; i < c.length; i++ ) {
                  value += i * c[i] * Math.pow( x, (int)i-1);
              }
          }
  
          return value;
      }
  
      /**
       * Compute the value for the second derivative of the function.
       * 
       * <p>This can be explicitly determined by 
       *   <tt>n * (n-1) * c_n * x^(n-2) + ... + 3 * 2 * c_3 * x  + 2 * c_2</tt>
       * </p>
       * 
       * @param x the point for which the first derivative should be computed
       * @return the value
       * @throws MathException if the second derivative couldn't be computed.
       */
      public double secondDerivative(double x) throws MathException {
  
          double value = 2.0 * c[2];
  
          if ( c.length > 2 ) {
              for (int i=3; i < c.length; i++ ) {
                  value += i * (i-1) * c[i] * Math.pow( x, (int)i-2);
              }
          }
  
          return value;
      }
  
  
      /** 
       * local power function using integer powers.
       * <p>The Math.pow() function always returns absolute value,
       *   and is a bit 'heavier' since it can handle double values
       *   for the exponential value.</p>
       * @param x any double value
       * @param n must be 0 or greater 
       * @return x^n (or 0 if n < 0 ).
       * @throws MathException if n < 0.
       */
  //     private double pow( double x, int n ) throws MathException {
  //         double value = x;
  //         if ( n < 0 ) {
  //             throw new MathException( "power n must be 0 or greater" );
  //         } else if ( n == 0 ) {
  //             // x^0 = 1 always.
  //             value = 1.0;
  //         } else {
  //             // only multiply for powers > 1.
  //             for (int i=1; i < n; i++) {
  //                 value *= x;
  //             }
  //         }
  
  //         System.out.println("pow:"+x+"^"+n+"="+value);
  //         return value;
  //     }
  
  }
  
  
  

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