Added min/max utility methods for RealField elements.

src/main/java/org/apache/commons/math4/util/MathUtils.java

@@ -19,6 +19,7 @@ package org.apache.commons.math4.util;
 
 import java.util.Arrays;
 
+import org.apache.commons.math4.RealFieldElement;
 import org.apache.commons.math4.exception.MathArithmeticException;
 import org.apache.commons.math4.exception.NotFiniteNumberException;
 import org.apache.commons.math4.exception.NullArgumentException;
@@ -109,6 +110,28 @@ public final class MathUtils {
          return a - TWO_PI * FastMath.floor((a + FastMath.PI - center) / TWO_PI);
      }
 
+     /** Find the maximum of two field elements.
+      * @param <T> the type of the field elements
+      * @param e1 first element
+      * @param e2 second element
+      * @return max(a1, e2)
+      * @since 3.6
+      */
+     public static <T extends RealFieldElement<T>> T max(final T e1, final T e2) {
+         return e1.subtract(e2).getReal() >= 0 ? e1 : e2;
+     }
+
+     /** Find the minimum of two field elements.
+      * @param <T> the type of the field elements
+      * @param e1 first element
+      * @param e2 second element
+      * @return min(a1, e2)
+      * @since 3.6
+      */
+     public static <T extends RealFieldElement<T>> T min(final T e1, final T e2) {
+         return e1.subtract(e2).getReal() >= 0 ? e2 : e1;
+     }
+
     /**
      * <p>Reduce {@code |a - offset|} to the primary interval
      * {@code [0, |period|)}.</p>