Removed the log10 declaration in RealFieldElement interface.

This method introduced a binary incompatibility as one implementing
class (Dfp) did not have the proper return type and had to be changed.
The method will be added back in the interface for 4.0, when it will be
allowed to change the return type for Dfp.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1455053 13f79535-47bb-0310-9956-ffa450edef68

src/main/java/org/apache/commons/math3/RealFieldElement.java

@@ -205,10 +205,12 @@ public interface RealFieldElement<T> extends FieldElement<T> {
      */
     T log1p();
 
-    /** Base 10 logarithm.
+//    TODO: add this method in 4.0, as it is not possible to do it in 3.2
-     * @return base 10 logarithm of the instance
+//          due to incompatibility of the return type in the Dfp class
-     */
+//    /** Base 10 logarithm.
-    T log10();
+//     * @return base 10 logarithm of the instance
+//     */
+//    T log10();
 
     /** Cosine operation.
      * @return cos(this)

src/main/java/org/apache/commons/math3/analysis/differentiation/DerivativeStructure.java

@@ -621,7 +621,9 @@ public class DerivativeStructure implements RealFieldElement<DerivativeStructure
         return result;
     }
 
-    /** {@inheritDoc} */
+    /** Base 10 logarithm.
+     * @return base 10 logarithm of the instance
+     */
     public DerivativeStructure log10() {
         final DerivativeStructure result = new DerivativeStructure(compiler);
         compiler.log10(data, 0, result.data, 0);

src/main/java/org/apache/commons/math3/dfp/Dfp.java

@@ -2665,13 +2665,25 @@ public class Dfp implements RealFieldElement<Dfp> {
         return DfpMath.log(this.add(getOne()));
     }
 
-    /** {@inheritDoc}
+//  TODO: deactivate this implementation (and return type) in 4.0
-     * @since 3.2
+    /** Get the exponent of the greatest power of 10 that is less than or equal to abs(this).
+     *  @return integer base 10 logarithm
+     *  @deprecated as of 3.2, replaced by {@link #intLog10()}, in 4.0 the return type
+     *  will be changed to Dfp
      */
-    public Dfp log10() {
+    @Deprecated
-        return DfpMath.log(this).divide(DfpMath.log(newInstance(10)));
+    public int log10()  {
+        return intLog10();
     }
 
+//    TODO: activate this implementation (and return type) in 4.0
+//    /** {@inheritDoc}
+//     * @since 3.2
+//     */
+//    public Dfp log10() {
+//        return DfpMath.log(this).divide(DfpMath.log(newInstance(10)));
+//    }
+
     /** {@inheritDoc}
      * @since 3.2
      */

src/main/java/org/apache/commons/math3/util/Decimal64.java

@@ -442,7 +442,9 @@ public class Decimal64 extends Number
         return new Decimal64(FastMath.log1p(value));
     }
 
-    /** {@inheritDoc} */
+    /** Base 10 logarithm.
+     * @return base 10 logarithm of the instance
+     */
     public Decimal64 log10() {
         return new Decimal64(FastMath.log10(value));
     }

src/test/java/org/apache/commons/math3/ExtendedFieldElementAbstractTest.java

@@ -312,12 +312,14 @@ public abstract class ExtendedFieldElementAbstractTest<T extends RealFieldElemen
         }
     }
 
-    @Test
+//  TODO: add this test in 4.0, as it is not possible to do it in 3.2
-    public void testLog10() {
+//  due to incompatibility of the return type in the Dfp class
-        for (double x = -0.9; x < 0.9; x += 0.05) {
+//    @Test
-            checkRelative(FastMath.log10(x), build(x).log10());
+//    public void testLog10() {
-        }
+//        for (double x = -0.9; x < 0.9; x += 0.05) {
-    }
+//            checkRelative(FastMath.log10(x), build(x).log10());
+//        }
+//    }
 
     @Test
     public void testAbs() {