Add getXmax, getXmin, getYmax, getYmin to BicubicInterpolatingFunction.

These can be useful to manage an OutOfRangeException without the need to
access the original x and y arrays.

Closes #9.

src/changes/changes.xml

@@ -54,6 +54,11 @@ If the output is not quite correct, check for invisible trailing spaces!
     </release>
 
     <release version="4.0" date="XXXX-XX-XX" description="">
+      <action dev="luc" type="add" due-to="Lorenzoexe">
+        Add getXmax(), getXmin(), getYmax(), getYmin() to bicubic interpolating function.
+        These can be useful to manage an OutOfRangeException without the need to access
+        the original x and y arrays.
+      </action>
       <action dev="luc" type="add" >
         Added mapping functions to MathArrays. These methods allow to map
         any univariate or bivariate functions to arrays.

src/main/java/org/apache/commons/math4/analysis/interpolation/BicubicInterpolatingFunction.java

@@ -184,6 +184,38 @@ public class BicubicInterpolatingFunction
         }
     }
 
+    /**
+     * Returns the minimum value of the first coordinate
+     * @return xval[0].
+     */
+    public double getXmin() {
+        return xval[0];
+    }
+
+    /**
+     * Returns the maximum value of the second coordinate
+     * @return xval[xval.length - 1].
+     */
+    public double getXmax() {
+        return xval[xval.length - 1];
+    }
+
+    /**
+     * Returns the minimum value of the second coordinate
+     * @return yval[0].
+     */
+    public double getYmin() {
+        return yval[0];
+    }
+
+    /**
+     * Returns the maximum value of the second coordinate
+     * @return yval[yval.length - 1].
+     */
+    public double getYmax() {
+        return yval[yval.length - 1];
+    }
+
     /**
      * @param c Coordinate.
      * @param val Coordinate samples.

src/test/java/org/apache/commons/math4/analysis/interpolation/BicubicInterpolatingFunctionTest.java

@@ -160,7 +160,12 @@ public final class BicubicInterpolatingFunctionTest {
         try {
             bcf.value(x, y);
             Assert.fail("OutOfRangeException expected");
-        } catch (OutOfRangeException expected) {}
+        } catch (OutOfRangeException expected) {
+            Assert.assertEquals(xMin, bcf.getXmin(), 1.0e-15);
+            Assert.assertEquals(xMax, bcf.getXmax(), 1.0e-15);
+            Assert.assertEquals(yMin, bcf.getYmin(), 1.0e-15);
+            Assert.assertEquals(yMax, bcf.getYmax(), 1.0e-15);
+        }
 
         x = xMin;
         y = yMax + small;
@@ -169,7 +174,12 @@ public final class BicubicInterpolatingFunctionTest {
         try {
             bcf.value(x, y);
             Assert.fail("OutOfRangeException expected");
-        } catch (OutOfRangeException expected) {}
+        } catch (OutOfRangeException expected) {
+            Assert.assertEquals(xMin, bcf.getXmin(), 1.0e-15);
+            Assert.assertEquals(xMax, bcf.getXmax(), 1.0e-15);
+            Assert.assertEquals(yMin, bcf.getYmin(), 1.0e-15);
+            Assert.assertEquals(yMax, bcf.getYmax(), 1.0e-15);
+        }
     }
 
     /**