svn commit: r179958 - in /jakarta/commons/proper/math/trunk/src: java/org/apache/commons/math/analysis/BrentSolver.java java/org/apache/commons/math/analysis/SecantSolver.java test/org/apache/commons/math/analysis/BrentSolverTest.java

[psteitz]

Author: psteitz
Date: Fri Jun  3 22:36:42 2005
New Revision: 179958

URL: http://svn.apache.org/viewcvs?rev=179958&view=rev
Log:
Eliminated redundant endpoint function evaluations in BrentSolver, 
SecantSolver. BZ #35042.

Modified:
    
jakarta/commons/proper/math/trunk/src/java/org/apache/commons/math/analysis/BrentSolver.java
    
jakarta/commons/proper/math/trunk/src/java/org/apache/commons/math/analysis/SecantSolver.java
    
jakarta/commons/proper/math/trunk/src/test/org/apache/commons/math/analysis/BrentSolverTest.java

Modified: 
jakarta/commons/proper/math/trunk/src/java/org/apache/commons/math/analysis/BrentSolver.java
URL: 
http://svn.apache.org/viewcvs/jakarta/commons/proper/math/trunk/src/java/org/apache/commons/math/analysis/BrentSolver.java?rev=179958&r1=179957&r2=179958&view=diff
==============================================================================
--- 
jakarta/commons/proper/math/trunk/src/java/org/apache/commons/math/analysis/BrentSolver.java
 (original)
+++ 
jakarta/commons/proper/math/trunk/src/java/org/apache/commons/math/analysis/BrentSolver.java
 Fri Jun  3 22:36:42 2005
@@ -1,5 +1,5 @@
 /*
- * Copyright 2003-2004 The Apache Software Foundation.
+ * Copyright 2003-2005 The Apache Software Foundation.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -82,7 +82,7 @@
         FunctionEvaluationException {
         
         clearResult();
-        verifyBracketing(min, max, f);
+        verifyInterval(min, max);
         
         // Index 0 is the old approximation for the root.
         // Index 1 is the last calculated approximation  for the root.
@@ -93,6 +93,14 @@
         double y1;
         y0 = f.value(x0);
         y1 = f.value(x1);
+        
+        // Verify bracketing
+        if (y0 * y1 >= 0) {
+            throw new IllegalArgumentException
+            ("Function values at endpoints do not have different signs." +
+                    "  Endpoints: [" + min + "," + max + "]" + 
+                    "  Values: [" + y0 + "," + y1 + "]");       
+        }
    
         double x2 = x0;
         double y2 = y0;

Modified: 
jakarta/commons/proper/math/trunk/src/java/org/apache/commons/math/analysis/SecantSolver.java
URL: 
http://svn.apache.org/viewcvs/jakarta/commons/proper/math/trunk/src/java/org/apache/commons/math/analysis/SecantSolver.java?rev=179958&r1=179957&r2=179958&view=diff
==============================================================================
--- 
jakarta/commons/proper/math/trunk/src/java/org/apache/commons/math/analysis/SecantSolver.java
 (original)
+++ 
jakarta/commons/proper/math/trunk/src/java/org/apache/commons/math/analysis/SecantSolver.java
 Fri Jun  3 22:36:42 2005
@@ -84,7 +84,7 @@
         FunctionEvaluationException {
         
         clearResult();
-        verifyBracketing(min, max, f);
+        verifyInterval(min, max);
         
         // Index 0 is the old approximation for the root.
         // Index 1 is the last calculated approximation  for the root.
@@ -95,6 +95,15 @@
         double x1 = max;
         double y0 = f.value(x0);
         double y1 = f.value(x1);
+        
+        // Verify bracketing
+        if (y0 * y1 >= 0) {
+            throw new IllegalArgumentException
+            ("Function values at endpoints do not have different signs." +
+                    "  Endpoints: [" + min + "," + max + "]" + 
+                    "  Values: [" + y0 + "," + y1 + "]");       
+        }
+        
         double x2 = x0;
         double y2 = y0;
         double oldDelta = x2 - x1;

Modified: 
jakarta/commons/proper/math/trunk/src/test/org/apache/commons/math/analysis/BrentSolverTest.java
URL: 
http://svn.apache.org/viewcvs/jakarta/commons/proper/math/trunk/src/test/org/apache/commons/math/analysis/BrentSolverTest.java?rev=179958&r1=179957&r2=179958&view=diff
==============================================================================
--- 
jakarta/commons/proper/math/trunk/src/test/org/apache/commons/math/analysis/BrentSolverTest.java
 (original)
+++ 
jakarta/commons/proper/math/trunk/src/test/org/apache/commons/math/analysis/BrentSolverTest.java
 Fri Jun  3 22:36:42 2005
@@ -266,4 +266,21 @@
         result = UnivariateRealSolverUtils.solve(f, 0.85, 5);
         assertEquals(result, 1.0, 1E-6);
     }
+    
+    public void testBadEndpoints() throws Exception {
+        UnivariateRealFunction f = new SinFunction();
+        UnivariateRealSolver solver = new BrentSolver(f);
+        try {  // bad interval
+            solver.solve(1, -1);
+            fail("Expecting IllegalArgumentException - bad interval");
+        } catch (IllegalArgumentException ex) {
+            // expected
+        }
+        try {  // no bracket
+            solver.solve(1, 1.5);
+            fail("Expecting IllegalArgumentException - non-bracketing");
+        } catch (IllegalArgumentException ex) {
+            // expected
+        }
+    }
 }



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