Merge pull request Hipparchus-Math#282 from Serrof/issue-280

Fix Hipparchus-Math#280: add square to FiedElement
Serrof · Nov 5, 2023 · 43dcbbd · 43dcbbd
2 parents 40472e8 + 963d985
commit 43dcbbd
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diff --git a/hipparchus-core/src/changes/changes.xml b/hipparchus-core/src/changes/changes.xml
@@ -49,6 +49,11 @@ If the output is not quite correct, check for invisible trailing spaces!
     <title>Hipparchus Core Release Notes</title>
   </properties>
   <body>
+    <release version="3.1" date="TBD" description="TBD.">
+      <action dev="serrof" type="add" issue="issues/280">
+        Add square method to FieldElement.
+      </action>
+    </release>
     <release version="3.0" date="2023-10-08" description="This is a major release.">
       <action dev="serrof" type="fix" issue="issues/275">
         UnivariateDerivative now implements Comparable.

diff --git a/hipparchus-core/src/main/java/org/hipparchus/CalculusFieldElement.java b/hipparchus-core/src/main/java/org/hipparchus/CalculusFieldElement.java
@@ -137,6 +137,12 @@ T hypot(T y)
      */
     T rootN(int n);
 
+    /** {@inheritDoc} */
+    @Override
+    default T square() {
+        return pow(2);
+    }
+
     /** Power operation.
      * @param p power to apply
      * @return this<sup>p</sup>

diff --git a/hipparchus-core/src/main/java/org/hipparchus/FieldElement.java b/hipparchus-core/src/main/java/org/hipparchus/FieldElement.java
@@ -74,6 +74,12 @@ public interface FieldElement<T extends FieldElement<T>> {
      */
     T multiply(T a) throws NullArgumentException;
 
+    /** Compute this &times; this.
+     * @return a new element representing this &times; this
+     * @since 3.1
+     */
+    T square() throws NullArgumentException;
+
     /** Compute this &divide; a.
      * @param a element to divide by
      * @return a new element representing this &divide; a

diff --git a/hipparchus-core/src/main/java/org/hipparchus/analysis/differentiation/DSCompiler.java b/hipparchus-core/src/main/java/org/hipparchus/analysis/differentiation/DSCompiler.java
@@ -2508,7 +2508,7 @@ public <T extends CalculusFieldElement<T>> void acos(final T[] operand, final in
             // as per polynomial parity, we can store coefficients of both P_(n-1) and P_n in the same array
             final T[] p = MathArrays.buildArray(field, order);
             p[0] = field.getOne().negate();
-            final T x2    = x.multiply(x);
+            final T x2    = x.square();
             final T f     = x2.subtract(1).negate().reciprocal();
             T coeff = f.sqrt();
             function[1] = coeff.multiply(p[0]);
@@ -2625,7 +2625,7 @@ public <T extends CalculusFieldElement<T>> void asin(final T[] operand, final in
             // as per polynomial parity, we can store coefficients of both P_(n-1) and P_n in the same array
             final T[] p = MathArrays.buildArray(field, order);
             p[0] = field.getOne();
-            final T x2    = x.multiply(x);
+            final T x2    = x.square();
             final T f     = x2.subtract(1).negate().reciprocal();
             T coeff = f.sqrt();
             function[1] = coeff.multiply(p[0]);
@@ -2742,7 +2742,7 @@ public <T extends CalculusFieldElement<T>> void atan(final T[] operand, final in
             // as per polynomial parity, we can store coefficients of both Q_(n-1) and Q_n in the same array
             final T[] q = MathArrays.buildArray(field, order);
             q[0] = field.getOne();
-            final T x2    = x.multiply(x);
+            final T x2    = x.square();
             final T f     = x2.add(1).reciprocal();
             T coeff = f;
             function[1] = coeff.multiply(q[0]);
@@ -3261,7 +3261,7 @@ public <T extends CalculusFieldElement<T>> void acosh(final T[] operand, final i
             // as per polynomial parity, we can store coefficients of both P_(n-1) and P_n in the same array
             final T[] p = MathArrays.buildArray(field, order);
             p[0] = field.getOne();
-            final T x2  = x.multiply(x);
+            final T x2  = x.square();
             final T f   = x2.subtract(1).reciprocal();
             T coeff = f.sqrt();
             function[1] = coeff.multiply(p[0]);
@@ -3378,7 +3378,7 @@ public <T extends CalculusFieldElement<T>> void asinh(final T[] operand, final i
             // as per polynomial parity, we can store coefficients of both P_(n-1) and P_n in the same array
             final T[] p = MathArrays.buildArray(field, order);
             p[0] = field.getOne();
-            final T x2    = x.multiply(x);
+            final T x2    = x.square();
             final T f     = x2.add(1).reciprocal();
             T coeff = f.sqrt();
             function[1] = coeff.multiply(p[0]);
@@ -3495,7 +3495,7 @@ public <T extends CalculusFieldElement<T>> void atanh(final T[] operand, final i
             // as per polynomial parity, we can store coefficients of both Q_(n-1) and Q_n in the same array
             final T[] q = MathArrays.buildArray(field, order);
             q[0] = field.getOne();
-            final T x2 = x.multiply(x);
+            final T x2 = x.square();
             final T f  =x2.subtract(1).negate().reciprocal();
             T coeff = f;
             function[1] = coeff.multiply(q[0]);

diff --git a/...rchus-core/src/main/java/org/hipparchus/analysis/differentiation/DerivativeStructure.java b/...rchus-core/src/main/java/org/hipparchus/analysis/differentiation/DerivativeStructure.java
@@ -250,6 +250,12 @@ public DerivativeStructure multiply(final DerivativeStructure a)
         return result;
     }
 
+    /** {@inheritDoc} */
+    @Override
+    public DerivativeStructure square() {
+        return multiply(this);
+    }
+
     /** {@inheritDoc}
      */
     @Override

diff --git a/...-core/src/main/java/org/hipparchus/analysis/differentiation/FieldDerivativeStructure.java b/...-core/src/main/java/org/hipparchus/analysis/differentiation/FieldDerivativeStructure.java
@@ -258,6 +258,12 @@ public FieldDerivativeStructure<T> multiply(final FieldDerivativeStructure<T> a)
         return result;
     }
 
+    /** {@inheritDoc} */
+    @Override
+    public FieldDerivativeStructure<T> square() {
+        return multiply(this);
+    }
+
     /** '&divide;' operator.
      * @param a right hand side parameter of the operator
      * @return this&divide;a

diff --git a/hipparchus-core/src/main/java/org/hipparchus/analysis/differentiation/FieldGradient.java b/hipparchus-core/src/main/java/org/hipparchus/analysis/differentiation/FieldGradient.java
@@ -330,6 +330,16 @@ public FieldGradient<T> multiply(final FieldGradient<T> a) {
         return result;
     }
 
+    /** {@inheritDoc} */
+    @Override
+    public FieldGradient<T> square() {
+        final FieldGradient<T> result = newInstance(value.square());
+        for (int i = 0; i < grad.length; ++i) {
+            result.grad[i] = grad[i].multiply(value).multiply(2);
+        }
+        return result;
+    }
+
     /** '&divide;' operator.
      * @param a right hand side parameter of the operator
      * @return this&divide;a
@@ -580,7 +590,7 @@ public FieldGradient<T> sqrt() {
     @Override
     public FieldGradient<T> cbrt() {
         final T c = FastMath.cbrt(value);
-        return compose(c, c.multiply(c).multiply(3).reciprocal());
+        return compose(c, c.square().multiply(3).reciprocal());
     }
 
     /** {@inheritDoc} */
@@ -721,25 +731,25 @@ public FieldGradient<T> tan() {
     /** {@inheritDoc} */
     @Override
     public FieldGradient<T> acos() {
-        return compose(FastMath.acos(value), value.multiply(value).negate().add(1).sqrt().reciprocal().negate());
+        return compose(FastMath.acos(value), value.square().negate().add(1).sqrt().reciprocal().negate());
     }
 
     /** {@inheritDoc} */
     @Override
     public FieldGradient<T> asin() {
-        return compose(FastMath.asin(value), value.multiply(value).negate().add(1).sqrt().reciprocal());
+        return compose(FastMath.asin(value), value.square().negate().add(1).sqrt().reciprocal());
     }
 
     /** {@inheritDoc} */
     @Override
     public FieldGradient<T> atan() {
-        return compose(FastMath.atan(value), value.multiply(value).add(1).reciprocal());
+        return compose(FastMath.atan(value), value.square().add(1).reciprocal());
     }
 
     /** {@inheritDoc} */
     @Override
     public FieldGradient<T> atan2(final FieldGradient<T> x) {
-        final T inv = value.multiply(value).add(x.value.multiply(x.value)).reciprocal();
+        final T inv = value.square().add(x.value.multiply(x.value)).reciprocal();
         final FieldGradient<T> result = newInstance(FastMath.atan2(value, x.value));
         final T xValueInv = x.value.multiply(inv);
         final T mValueInv = value.negate().multiply(inv);
@@ -784,19 +794,19 @@ public FieldGradient<T> tanh() {
     /** {@inheritDoc} */
     @Override
     public FieldGradient<T> acosh() {
-        return compose(FastMath.acosh(value), value.multiply(value).subtract(1).sqrt().reciprocal());
+        return compose(FastMath.acosh(value), value.square().subtract(1).sqrt().reciprocal());
     }
 
     /** {@inheritDoc} */
     @Override
     public FieldGradient<T> asinh() {
-        return compose(FastMath.asinh(value), value.multiply(value).add(1).sqrt().reciprocal());
+        return compose(FastMath.asinh(value), value.square().add(1).sqrt().reciprocal());
     }
 
     /** {@inheritDoc} */
     @Override
     public FieldGradient<T> atanh() {
-        return compose(FastMath.atanh(value), value.multiply(value).negate().add(1).reciprocal());
+        return compose(FastMath.atanh(value), value.square().negate().add(1).reciprocal());
     }
 
     /** {@inheritDoc} */

diff --git a/...ore/src/main/java/org/hipparchus/analysis/differentiation/FieldUnivariateDerivative1.java b/...ore/src/main/java/org/hipparchus/analysis/differentiation/FieldUnivariateDerivative1.java
@@ -218,6 +218,12 @@ public FieldUnivariateDerivative1<T> multiply(final FieldUnivariateDerivative1<T
                                                 a.f0.linearCombination(f1, a.f0, f0, a.f1));
     }
 
+    /** {@inheritDoc} */
+    @Override
+    public FieldUnivariateDerivative1<T> square() {
+        return multiply(this);
+    }
+
     /** '&divide;' operator.
      * @param a right hand side parameter of the operator
      * @return this&divide;a
@@ -441,7 +447,7 @@ public FieldUnivariateDerivative1<T> sqrt() {
     @Override
     public FieldUnivariateDerivative1<T> cbrt() {
         final T c = FastMath.cbrt(f0);
-        return compose(c, c.multiply(c).multiply(3).reciprocal());
+        return compose(c, c.square().multiply(3).reciprocal());
     }
 
     /** {@inheritDoc} */

diff --git a/...ore/src/main/java/org/hipparchus/analysis/differentiation/FieldUnivariateDerivative2.java b/...ore/src/main/java/org/hipparchus/analysis/differentiation/FieldUnivariateDerivative2.java
@@ -236,6 +236,12 @@ public FieldUnivariateDerivative2<T> multiply(final FieldUnivariateDerivative2<T
                                                 a.f0.linearCombination(f2, a.f0, f1.add(f1), a.f1, f0, a.f2));
     }
 
+    /** {@inheritDoc} */
+    @Override
+    public FieldUnivariateDerivative2<T> square() {
+        return multiply(this);
+    }
+
     /** '&divide;' operator.
      * @param a right hand side parameter of the operator
      * @return this&divide;a
@@ -484,7 +490,7 @@ public FieldUnivariateDerivative2<T> sqrt() {
     @Override
     public FieldUnivariateDerivative2<T> cbrt() {
         final T c  = FastMath.cbrt(f0);
-        final T c2 = c.multiply(c);
+        final T c2 = c.square();
         return compose(c, c2.multiply(3).reciprocal(), c2.multiply(-4.5).multiply(f0).reciprocal());
     }
 
@@ -498,7 +504,7 @@ public FieldUnivariateDerivative2<T> rootN(final int n) {
         } else {
             final T r = FastMath.pow(f0, 1.0 / n);
             final T z = FastMath.pow(r, n - 1).multiply(n);
-            return compose(r, z.reciprocal(), z.multiply(z).multiply(r).reciprocal().multiply(1 -n));
+            return compose(r, z.reciprocal(), z.square().multiply(r).reciprocal().multiply(1 -n));
         }
     }
 

diff --git a/hipparchus-core/src/main/java/org/hipparchus/analysis/differentiation/Gradient.java b/hipparchus-core/src/main/java/org/hipparchus/analysis/differentiation/Gradient.java
@@ -19,7 +19,6 @@
 import java.io.Serializable;
 import java.util.Arrays;
 
-import org.hipparchus.CalculusFieldElement;
 import org.hipparchus.exception.LocalizedCoreFormats;
 import org.hipparchus.exception.MathIllegalArgumentException;
 import org.hipparchus.util.FastMath;
@@ -54,7 +53,7 @@
  * @see FieldGradient
  * @since 1.7
  */
-public class Gradient implements Derivative<Gradient>, CalculusFieldElement<Gradient>, Serializable {
+public class Gradient implements Derivative<Gradient>, Serializable {
 
     /** Serializable UID. */
     private static final long serialVersionUID = 20200520L;
@@ -274,6 +273,16 @@ public Gradient multiply(final Gradient a) {
         return result;
     }
 
+    /** {@inheritDoc} */
+    @Override
+    public Gradient square() {
+        final Gradient result = newInstance(value * value);
+        for (int i = 0; i < grad.length; ++i) {
+            result.grad[i] = 2 * grad[i] * value;
+        }
+        return result;
+    }
+
     /** {@inheritDoc} */
     @Override
     public Gradient divide(final double a) {

diff --git a/hipparchus-core/src/main/java/org/hipparchus/analysis/differentiation/SparseGradient.java b/hipparchus-core/src/main/java/org/hipparchus/analysis/differentiation/SparseGradient.java
@@ -281,6 +281,12 @@ public SparseGradient multiply(final int n) {
         return new SparseGradient(value * n, n, derivatives);
     }
 
+    /** {@inheritDoc} */
+    @Override
+    public SparseGradient square() {
+        return multiply(this);
+    }
+
     /** {@inheritDoc} */
     @Override
     public SparseGradient divide(final SparseGradient a) {
@@ -698,7 +704,7 @@ public SparseGradient atan() {
     public SparseGradient atan2(final SparseGradient x) {
 
         // compute r = sqrt(x^2+y^2)
-        final SparseGradient r = multiply(this).add(x.multiply(x)).sqrt();
+        final SparseGradient r = square().add(x.square()).sqrt();
 
         final SparseGradient a;
         if (x.value >= 0) {

diff --git a/...hus-core/src/main/java/org/hipparchus/analysis/differentiation/UnivariateDerivative1.java b/...hus-core/src/main/java/org/hipparchus/analysis/differentiation/UnivariateDerivative1.java
@@ -182,6 +182,12 @@ public UnivariateDerivative1 multiply(final UnivariateDerivative1 a) {
                                          MathArrays.linearCombination(f1, a.f0, f0, a.f1));
     }
 
+    /** {@inheritDoc} */
+    @Override
+    public UnivariateDerivative1 square() {
+        return new UnivariateDerivative1(f0 * f0, 2 * f0 * f1);
+    }
+
     /** {@inheritDoc} */
     @Override
     public UnivariateDerivative1 divide(final double a) {

diff --git a/...hus-core/src/main/java/org/hipparchus/analysis/differentiation/UnivariateDerivative2.java b/...hus-core/src/main/java/org/hipparchus/analysis/differentiation/UnivariateDerivative2.java
@@ -201,6 +201,12 @@ public UnivariateDerivative2 multiply(final UnivariateDerivative2 a) {
                                          MathArrays.linearCombination(f2, a.f0, 2 * f1, a.f1, f0, a.f2));
     }
 
+    /** {@inheritDoc} */
+    @Override
+    public UnivariateDerivative2 square() {
+        return new UnivariateDerivative2(f0 * f0, 2 * f0 * f1, 2 * (f0 * f2 + f1 * f1));
+    }
+
     /** {@inheritDoc} */
     @Override
     public UnivariateDerivative2 divide(final double a) {

diff --git a/...core/src/main/java/org/hipparchus/analysis/integration/gauss/FieldHermiteRuleFactory.java b/...core/src/main/java/org/hipparchus/analysis/integration/gauss/FieldHermiteRuleFactory.java
@@ -78,7 +78,7 @@ protected Pair<T[], T[]> computeRule(int numberOfPoints)
         final Hermite<T> hm1 = new Hermite<>(field, numberOfPoints - 1);
         for (int i = 0; i < numberOfPoints; i++) {
             final T y = hm1.hNhNm1(points[i])[0];
-            weights[i] = sqrtPi.divide(y.multiply(y).multiply(numberOfPoints));
+            weights[i] = sqrtPi.divide(y.square().multiply(numberOfPoints));
         }
 
         return new Pair<>(points, weights);

diff --git a/...ore/src/main/java/org/hipparchus/analysis/integration/gauss/FieldLaguerreRuleFactory.java b/...ore/src/main/java/org/hipparchus/analysis/integration/gauss/FieldLaguerreRuleFactory.java
@@ -57,7 +57,7 @@ public Pair<T[], T[]> computeRule(int numberOfPoints)
         final Laguerre<T> laguerreN1 = new Laguerre<>(n1);
         for (int i = 0; i < numberOfPoints; i++) {
             final T y = laguerreN1.value(points[i]);
-            weights[i] = points[i].divide(y.multiply(y).multiply(n1Squared));
+            weights[i] = points[i].divide(y.square().multiply(n1Squared));
         }
 
         return new Pair<>(points, weights);

diff --git a/...ore/src/main/java/org/hipparchus/analysis/integration/gauss/FieldLegendreRuleFactory.java b/...ore/src/main/java/org/hipparchus/analysis/integration/gauss/FieldLegendreRuleFactory.java
@@ -70,7 +70,7 @@ public Pair<T[], T[]> computeRule(int numberOfPoints)
             final T c = points[i];
             final T[] pKpKm1 = p.pNpNm1(c);
             final T d = pKpKm1[1].subtract(c.multiply(pKpKm1[0])).multiply(numberOfPoints);
-            weights[i] = c.multiply(c).subtract(1).multiply(-2).divide(d.multiply(d));
+            weights[i] = c.square().subtract(1).multiply(-2).divide(d.multiply(d));
 
             // symmetrical point
             final int idx = numberOfPoints - i - 1;