MATH-1572: Simplify conditional expressions

* Simplify bitwise
* Simplify boolean expression
* Simplify conditional expression
* Redundant 'if' statement

commons-math-legacy-core/src/main/java/org/apache/commons/math4/legacy/core/MathArrays.java

@@ -617,7 +617,7 @@ public final class MathArrays {
      */
     public static boolean equals(float[] x, float[] y) {
         if (x == null || y == null) {
-            return !((x == null) ^ (y == null));
+            return (x == null) == (y == null);
         }
         if (x.length != y.length) {
             return false;
@@ -643,7 +643,7 @@ public final class MathArrays {
      */
     public static boolean equalsIncludingNaN(float[] x, float[] y) {
         if (x == null || y == null) {
-            return !((x == null) ^ (y == null));
+            return (x == null) == (y == null);
         }
         if (x.length != y.length) {
             return false;
@@ -668,7 +668,7 @@ public final class MathArrays {
      */
     public static boolean equals(double[] x, double[] y) {
         if (x == null || y == null) {
-            return !((x == null) ^ (y == null));
+            return (x == null) == (y == null);
         }
         if (x.length != y.length) {
             return false;
@@ -694,7 +694,7 @@ public final class MathArrays {
      */
     public static boolean equalsIncludingNaN(double[] x, double[] y) {
         if (x == null || y == null) {
-            return !((x == null) ^ (y == null));
+            return (x == null) == (y == null);
         }
         if (x.length != y.length) {
             return false;

commons-math-legacy-core/src/main/java/org/apache/commons/math4/legacy/core/dfp/Dfp.java

@@ -2351,10 +2351,7 @@ public class Dfp implements RealFieldElement<Dfp> {
         }
 
         // if this is greater than x
-        boolean up = false;
+        boolean up = this.lessThan(x);
-        if (this.lessThan(x)) {
-            up = true;
-        }
 
         if (compare(this, x) == 0) {
             return newInstance(x);

commons-math-legacy-core/src/main/java/org/apache/commons/math4/legacy/core/dfp/DfpMath.java

@@ -941,11 +941,7 @@ public final class DfpMath {
      */
     public static Dfp acos(Dfp a) {
         Dfp result;
-        boolean negative = false;
+        boolean negative = a.lessThan(a.getZero());
-
-        if (a.lessThan(a.getZero())) {
-            negative = true;
-        }
 
         a = Dfp.copySign(a, a.getOne());  // absolute value
 

commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/analysis/polynomials/PolynomialFunction.java

@@ -371,10 +371,7 @@ public class PolynomialFunction implements UnivariateDifferentiableFunction, Ser
             return false;
         }
         PolynomialFunction other = (PolynomialFunction) obj;
-        if (!Arrays.equals(coefficients, other.coefficients)) {
+        return Arrays.equals(coefficients, other.coefficients);
-            return false;
-        }
-        return true;
     }
 
     /**

commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/fitting/SimpleCurveFitter.java

@@ -186,11 +186,7 @@ public class SimpleCurveFitter extends AbstractCurveFitter {
                     if (comp != 0) {
                         return comp;
                     }
-                    comp = Double.compare(p1.getWeight(), p2.getWeight());
+                    return Double.compare(p1.getWeight(), p2.getWeight());
-                    if (comp != 0) {
-                        return comp;
-                    }
-                    return 0;
                 }
             };
 

commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/ode/events/EventState.java

@@ -365,7 +365,7 @@ public class EventState {
             // force the sign to its value "just after the event"
             previousEventTime = t;
             g0Positive        = increasing;
-            nextAction        = handler.eventOccurred(t, y, !(increasing ^ forward));
+            nextAction        = handler.eventOccurred(t, y, increasing == forward);
         } else {
             g0Positive = g0 >= 0;
             nextAction = EventHandler.Action.CONTINUE;

commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/ode/events/FieldEventState.java

@@ -301,7 +301,7 @@ public class FieldEventState<T extends RealFieldElement<T>> {
             // force the sign to its value "just after the event"
             previousEventTime = state.getTime();
             g0Positive        = increasing;
-            nextAction        = handler.eventOccurred(state, !(increasing ^ forward));
+            nextAction        = handler.eventOccurred(state, increasing == forward);
         } else {
             g0Positive = g0.getReal() >= 0;
             nextAction = Action.CONTINUE;

commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/optim/linear/SolutionCallback.java

@@ -57,6 +57,6 @@ public class SolutionCallback implements OptimizationData {
      * @return {@code true} if the solution is optimal, {@code false} otherwise
      */
     public boolean isSolutionOptimal() {
-        return tableau != null ? tableau.isOptimal() : false;
+        return tableau != null && tableau.isOptimal();
     }
 }

commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/optim/nonlinear/scalar/noderiv/CMAESOptimizer.java

@@ -896,7 +896,7 @@ public class CMAESOptimizer
         @Override
         public int hashCode() {
             long bits = Double.doubleToLongBits(value);
-            return (int) ((1438542 ^ (bits >>> 32) ^ bits) & 0xffffffff);
+            return (int) ((1438542 ^ (bits >>> 32) ^ bits));
         }
     }
     /**

commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/stat/Frequency.java

@@ -376,14 +376,7 @@ public class Frequency<T extends Comparable<T>> implements Serializable {
             return false;
         }
         Frequency<?> other = (Frequency<?>) obj;
-        if (freqTable == null) {
+        return freqTable.equals(other.freqTable);
-            if (other.freqTable != null) {
-                return false;
-            }
-        } else if (!freqTable.equals(other.freqTable)) {
-            return false;
-        }
-        return true;
     }
 
 }

commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/stat/descriptive/moment/VectorialCovariance.java

@@ -148,10 +148,7 @@ public class VectorialCovariance implements Serializable {
         if (!Arrays.equals(productsSums, other.productsSums)) {
             return false;
         }
-        if (!Arrays.equals(sums, other.sums)) {
+        return Arrays.equals(sums, other.sums);
-            return false;
-        }
-        return true;
     }
 
 }

commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/stat/descriptive/moment/VectorialMean.java

@@ -96,10 +96,7 @@ public class VectorialMean implements Serializable {
             return false;
         }
         VectorialMean other = (VectorialMean) obj;
-        if (!Arrays.equals(means, other.means)) {
+        return Arrays.equals(means, other.means);
-            return false;
-        }
-        return true;
     }
 
 }

commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/stat/descriptive/rank/PSquarePercentile.java

@@ -908,7 +908,7 @@ public class PSquarePercentile extends AbstractStorelessUnivariateStatistic
          */
         @Override
         public boolean add(final E e) {
-            return size() < capacity ? super.add(e) : false;
+            return size() < capacity && super.add(e);
         }
 
         /**
@@ -924,7 +924,7 @@ public class PSquarePercentile extends AbstractStorelessUnivariateStatistic
             boolean isCollectionLess =
                     collection != null &&
                             collection.size() + size() <= capacity;
-            return isCollectionLess ? super.addAll(collection) : false;
+            return isCollectionLess && super.addAll(collection);
         }
     }
 

commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/stat/inference/KolmogorovSmirnovTest.java

@@ -1132,11 +1132,7 @@ public class KolmogorovSmirnovTest {
            throw new InsufficientDataException();
        }
 
-       if (values.length == x.length + y.length) {
+        return values.length != x.length + y.length;  // There are no ties.
-           return false;  // There are no ties.
-       }
-
-       return true;
     }
 
     /**