Changed the return type of the various interpolation algorithms to the

specific implementation of UnivariateRealFunction each one uses
(thanks to Gilles for reporting the problem and providing the patch)


git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@794709 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/commons/math/analysis/interpolation/DividedDifferenceInterpolator.java

@@ -19,7 +19,6 @@ package org.apache.commons.math.analysis.interpolation;
 import java.io.Serializable;
 
 import org.apache.commons.math.DuplicateSampleAbscissaException;
-import org.apache.commons.math.analysis.UnivariateRealFunction;
 import org.apache.commons.math.analysis.polynomials.PolynomialFunctionLagrangeForm;
 import org.apache.commons.math.analysis.polynomials.PolynomialFunctionNewtonForm;
 
@@ -50,7 +49,7 @@ public class DividedDifferenceInterpolator implements UnivariateRealInterpolator
      * @return a function which interpolates the data set
      * @throws DuplicateSampleAbscissaException if arguments are invalid
      */
-    public UnivariateRealFunction interpolate(double x[], double y[]) throws
+    public PolynomialFunctionNewtonForm interpolate(double x[], double y[]) throws
         DuplicateSampleAbscissaException {
 
         /**
@@ -76,9 +75,8 @@ public class DividedDifferenceInterpolator implements UnivariateRealInterpolator
         }
         a = computeDividedDifference(x, y);
 
-        PolynomialFunctionNewtonForm p;
-        p = new PolynomialFunctionNewtonForm(a, c);
-        return p;
+        return new PolynomialFunctionNewtonForm(a, c);
+
     }
 
     /**

src/java/org/apache/commons/math/analysis/interpolation/LoessInterpolator.java

@@ -16,12 +16,12 @@
  */
 package org.apache.commons.math.analysis.interpolation;
 
-import org.apache.commons.math.analysis.UnivariateRealFunction;
-import org.apache.commons.math.MathException;
-
 import java.io.Serializable;
 import java.util.Arrays;
 
+import org.apache.commons.math.MathException;
+import org.apache.commons.math.analysis.polynomials.PolynomialSplineFunction;
+
 /**
  * Implements the <a href="http://en.wikipedia.org/wiki/Local_regression">
  * Local Regression Algorithm</a> (also Loess, Lowess) for interpolation of
@@ -132,7 +132,7 @@ public class LoessInterpolator
      * <li> All arguments and values are finite real numbers</li>
      * </ul>
      */
-    public final UnivariateRealFunction interpolate(
+    public final PolynomialSplineFunction interpolate(
             final double[] xval, final double[] yval) throws MathException {
         return new SplineInterpolator().interpolate(xval, smooth(xval, yval));
     }

src/java/org/apache/commons/math/analysis/interpolation/NevilleInterpolator.java

@@ -17,8 +17,8 @@
 package org.apache.commons.math.analysis.interpolation;
 
 import java.io.Serializable;
+
 import org.apache.commons.math.MathException;
-import org.apache.commons.math.analysis.UnivariateRealFunction;
 import org.apache.commons.math.analysis.polynomials.PolynomialFunctionLagrangeForm;
 
 /**
@@ -47,11 +47,8 @@ public class NevilleInterpolator implements UnivariateRealInterpolator,
      * @return a function which interpolates the data set
      * @throws MathException if arguments are invalid
      */
-    public UnivariateRealFunction interpolate(double x[], double y[]) throws
-        MathException {
-
-        PolynomialFunctionLagrangeForm p;
-        p = new PolynomialFunctionLagrangeForm(x, y);
-        return p;
+    public PolynomialFunctionLagrangeForm interpolate(double x[], double y[])
+        throws MathException {
+        return new PolynomialFunctionLagrangeForm(x, y);
     }
 }

src/java/org/apache/commons/math/analysis/interpolation/SplineInterpolator.java

@@ -17,7 +17,6 @@
 package org.apache.commons.math.analysis.interpolation;
 
 import org.apache.commons.math.MathRuntimeException;
-import org.apache.commons.math.analysis.UnivariateRealFunction;
 import org.apache.commons.math.analysis.polynomials.PolynomialFunction;
 import org.apache.commons.math.analysis.polynomials.PolynomialSplineFunction;
 
@@ -56,7 +55,7 @@ public class SplineInterpolator implements UnivariateRealInterpolator {
      * @param y the values for the interpolation points
      * @return a function which interpolates the data set
      */
-    public UnivariateRealFunction interpolate(double x[], double y[]) {
+    public PolynomialSplineFunction interpolate(double x[], double y[]) {
         if (x.length != y.length) {
             throw MathRuntimeException.createIllegalArgumentException(
                   "dimension mismatch {0} != {1}", x.length, y.length);

src/site/xdoc/changes.xml

@@ -39,6 +39,10 @@ The <action> type attribute can be add,update,fix,remove.
   </properties>
   <body>
     <release version="2.0" date="TBD" description="TBD">
+      <action dev="luc" type="update" due-to="Gilles Sadowski">
+        Changed the return type of the various interpolation algorithms to the
+        specific implementation of UnivariateRealFunction each one uses
+      </action>
       <action dev="luc" type="fix" issue="MATH-280">
         The behavior of the bracket method in UnivariateRealSolverUtils has been changed to return successfully
         when a tentative bracketing interval has a root exactly at one of its end points. Previously, such intervals