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    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.apache.commons.numbers.examples.jmh.complex;
  
  import org.apache.commons.numbers.complex.Complex;
  import org.apache.commons.rng.UniformRandomProvider;
  import org.apache.commons.rng.sampling.distribution.ZigguratNormalizedGaussianSampler;
  import org.apache.commons.rng.simple.RandomSource;
  import org.openjdk.jmh.annotations.Benchmark;
  import org.openjdk.jmh.annotations.BenchmarkMode;
  import org.openjdk.jmh.annotations.Fork;
  import org.openjdk.jmh.annotations.Measurement;
  import org.openjdk.jmh.annotations.Mode;
  import org.openjdk.jmh.annotations.OutputTimeUnit;
  import org.openjdk.jmh.annotations.Param;
  import org.openjdk.jmh.annotations.Scope;
  import org.openjdk.jmh.annotations.Setup;
  import org.openjdk.jmh.annotations.State;
  import org.openjdk.jmh.annotations.Warmup;
  import org.openjdk.jmh.infra.Blackhole;
  import java.util.Arrays;
  import java.util.concurrent.TimeUnit;
  import java.util.function.BiFunction;
  import java.util.function.Predicate;
  import java.util.function.Supplier;
  import java.util.function.ToDoubleFunction;
  import java.util.function.UnaryOperator;
  import java.util.stream.Stream;
  
  /**
   * Executes a benchmark to measure the speed of operations in the {@link Complex} class.
   */
  @BenchmarkMode(Mode.AverageTime)
  @OutputTimeUnit(TimeUnit.NANOSECONDS)
  @Warmup(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
  @Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
  @State(Scope.Benchmark)
  @Fork(value = 1, jvmArgs = {"-server", "-Xms512M", "-Xmx512M"})
  public class ComplexPerformance {
      /**
       * An array of edge numbers that will produce edge case results from functions:
       * {@code +/-inf, +/-max, +/-min, +/-0, nan}.
       */
      private static final double[] EDGE_NUMBERS = {
          Double.POSITIVE_INFINITY, Double.NEGATIVE_INFINITY, Double.MAX_VALUE,
          -Double.MAX_VALUE, Double.MIN_VALUE, -Double.MIN_VALUE, 0.0, -0.0, Double.NaN};
  
      /** The range to use for uniform random numbers. */
      private static final double RANGE = 3.456789;
  
      /**
       * Contains the size of numbers.
       */
      @State(Scope.Benchmark)
      public static class ComplexNumberSize {
          /**
           * The size of the data.
           */
          @Param({"10000"})
          private int size;
  
          /**
           * Gets the size.
           *
           * @return the size
           */
          public int getSize() {
              return size;
          }
      }
  
      /**
       * Contains an array of complex numbers.
       */
      @State(Scope.Benchmark)
      public static class ComplexNumbers extends ComplexNumberSize {
          /** The numbers. */
          protected Complex[] numbers;
  
          /**
           * The type of the data.
           */
          @Param({"cis", "vector", "log-uniform", "uniform", "edge"})
          private String type;
 
         /**
          * Gets the numbers.
          *
          * @return the numbers
          */
         public Complex[] getNumbers() {
             return numbers;
         }
 
         /**
          * Create the complex numbers.
          */
         @Setup
         public void setup() {
             numbers = createNumbers(RandomSource.XO_RO_SHI_RO_128_PP.create());
         }
 
         /**
          * Creates the numbers.
          *
          * @param rng Random number generator.
          * @return the random complex number
          */
         Complex[] createNumbers(UniformRandomProvider rng) {
             Supplier<Complex> generator;
             if ("cis".equals(type)) {
                 generator = () -> Complex.ofCis(rng.nextDouble() * 2 * Math.PI);
             } else if ("vector".equals(type)) {
                 // An unnormalised random vector is created using a Gaussian sample
                 // for each dimension. Normalisation would create a cis number.
                 // This is effectively a polar complex number with random modulus
                 // in [-pi, pi] and random magnitude in a range defined by a Chi-squared
                 // distribution with 2 degrees of freedom.
                 final ZigguratNormalizedGaussianSampler s = ZigguratNormalizedGaussianSampler.of(rng);
                 generator = () -> Complex.ofCartesian(s.sample(), s.sample());
             } else if ("log-uniform".equals(type)) {
                 generator = () -> Complex.ofCartesian(createLogUniformNumber(rng), createLogUniformNumber(rng));
             } else if ("uniform".equals(type)) {
                 generator = () -> Complex.ofCartesian(createUniformNumber(rng), createUniformNumber(rng));
             } else if ("edge".equals(type)) {
                 generator = () -> Complex.ofCartesian(createEdgeNumber(rng), createEdgeNumber(rng));
             } else {
                 throw new IllegalStateException("Unknown number type: " + type);
             }
             return Stream.generate(generator).limit(getSize()).toArray(Complex[]::new);
         }
     }
 
     /**
      * Contains two arrays of complex numbers.
      */
     @State(Scope.Benchmark)
     public static class TwoComplexNumbers extends ComplexNumbers {
         /** The numbers. */
         private Complex[] numbers2;
 
         /**
          * Gets the second set of numbers.
          *
          * @return the numbers
          */
         public Complex[] getNumbers2() {
             return numbers2;
         }
 
         /**
          * Create the complex numbers.
          */
         @Override
         @Setup
         public void setup() {
             // Do not call super.setup() so we recycle the RNG and avoid duplicates
             final UniformRandomProvider rng = RandomSource.XO_RO_SHI_RO_128_PP.create();
             numbers = createNumbers(rng);
             numbers2 = createNumbers(rng);
         }
     }
 
     /**
      * Contains an array of complex numbers and an array of real numbers.
      */
     @State(Scope.Benchmark)
     public static class ComplexAndRealNumbers extends ComplexNumbers {
         /** The numbers. */
         private double[] numbers2;
 
         /**
          * Gets the second set of numbers.
          *
          * @return the numbers
          */
         public double[] getNumbers2() {
             return numbers2;
         }
 
         /**
          * Create the complex numbers.
          */
         @Override
         @Setup
         public void setup() {
             // Do not call super.setup() so we recycle the RNG and avoid duplicates
             final UniformRandomProvider rng = RandomSource.XO_RO_SHI_RO_128_PP.create();
             numbers = createNumbers(rng);
             numbers2 = Arrays.stream(createNumbers(rng)).mapToDouble(Complex::real).toArray();
         }
     }
 
     /**
      * Define a function between a complex and real number.
      */
     private interface ComplexRealFunction {
         /**
          * Applies this function to the given arguments.
          *
          * @param z the complex argument
          * @param x the real argument
          * @return the function result
          */
         Complex apply(Complex z, double x);
     }
 
     /**
      * Creates a random double number with a random sign and mantissa and a large range for
      * the exponent. The numbers will not be uniform over the range. This samples randomly
      * using the components of a double. The limiting distribution is the log-uniform distribution.
      *
      * @param rng Random number generator.
      * @return the random number
      * @see <a href="https://en.wikipedia.org/wiki/Reciprocal_distribution">Reciprocal (log-uniform) distribution</a>
      */
     private static double createLogUniformNumber(UniformRandomProvider rng) {
         // Create random doubles using random bits in the sign bit and the mantissa.
         // Then create an exponent in the range -64 to 64. Thus the sum product
         // of 4 max or min values will not over or underflow.
         final long mask = ((1L << 52) - 1) | 1L << 63;
         final long bits = rng.nextLong() & mask;
         // The exponent must be unsigned so + 1023 to the signed exponent
         final long exp = rng.nextInt(129) - 64 + 1023;
         return Double.longBitsToDouble(bits | (exp << 52));
     }
 
     /**
      * Creates a random double number with a random sign and uniform range.
      *
      * @param rng Random number generator.
      * @return the random number
      */
     private static double createUniformNumber(UniformRandomProvider rng) {
         // Note: [0, 1) - 1 is [-1, 0).
         // Since the 1 is a 50/50 sample the result is the interval [-1, 1)
         // using the 2^54 dyadic rationals in the interval.
         // The range is not critical. The numbers will have approximately 50%
         // with the same exponent, max, matching that of RANGE and the rest smaller
         // exponents down to (max - 53) since the uniform deviate is limited to 2^-53.
         return (rng.nextDouble() - rng.nextInt(1)) * RANGE;
     }
 
     /**
      * Creates a random double number that will be an edge case:
      * {@code +/-inf, +/-max, +/-min, +/-0, nan}.
      *
      * @param rng Random number generator.
      * @return the random number
      */
     private static double createEdgeNumber(UniformRandomProvider rng) {
         return EDGE_NUMBERS[rng.nextInt(EDGE_NUMBERS.length)];
     }
 
     /**
      * Apply the function to all the numbers.
      *
      * @param numbers Numbers.
      * @param fun Function.
      * @param bh Data sink.
      */
     private static void apply(Complex[] numbers, Predicate<Complex> fun, Blackhole bh) {
         for (int i = 0; i < numbers.length; i++) {
             bh.consume(fun.test(numbers[i]));
         }
     }
 
     /**
      * Apply the function to all the numbers.
      *
      * @param numbers Numbers.
      * @param fun Function.
      * @param bh Data sink.
      */
     private static void apply(Complex[] numbers, ToDoubleFunction<Complex> fun, Blackhole bh) {
         for (int i = 0; i < numbers.length; i++) {
             bh.consume(fun.applyAsDouble(numbers[i]));
         }
     }
 
     /**
      * Apply the function to all the numbers.
      *
      * @param numbers Numbers.
      * @param fun Function.
      * @param bh Data sink.
      */
     private static void apply(Complex[] numbers, UnaryOperator<Complex> fun, Blackhole bh) {
         for (int i = 0; i < numbers.length; i++) {
             bh.consume(fun.apply(numbers[i]));
         }
     }
 
     /**
      * Apply the function to the paired numbers.
      *
      * @param numbers First numbers of the pairs.
      * @param numbers2 Second numbers of the pairs.
      * @param fun Function.
      * @param bh Data sink.
      */
     private static void apply(Complex[] numbers, Complex[] numbers2,
             BiFunction<Complex, Complex, Complex> fun, Blackhole bh) {
         for (int i = 0; i < numbers.length; i++) {
             bh.consume(fun.apply(numbers[i], numbers2[i]));
         }
     }
 
     /**
      * Apply the function to the paired numbers.
      *
      * @param numbers First numbers of the pairs.
      * @param numbers2 Second numbers of the pairs.
      * @param fun Function.
      * @param bh Data sink.
      */
     private static void apply(Complex[] numbers, double[] numbers2,
             ComplexRealFunction fun, Blackhole bh) {
         for (int i = 0; i < numbers.length; i++) {
             bh.consume(fun.apply(numbers[i], numbers2[i]));
         }
     }
 
     /**
      * Identity function. This can be used to measure overhead of object array creation.
      *
      * @param z Complex number.
      * @return the complex number
      */
     private static Complex identity(Complex z) {
         return z;
     }
 
     /**
      * Copy function. This can be used to measure overhead of object array creation plus
      * new Complex creation.
      *
      * @param z Complex number.
      * @return a copy of the complex number
      */
     private static Complex copy(Complex z) {
         return Complex.ofCartesian(z.real(), z.imag());
     }
 
     // Benchmark methods.
     //
     // The methods are partially documented as the names are self-documenting.
     // CHECKSTYLE: stop JavadocMethod
     // CHECKSTYLE: stop DesignForExtension
     //
     // Benchmarks use function references to perform different operations on the complex numbers.
     // Tests show that explicit programming of the same benchmarks run in the same time.
     // For reference examples are provided for the fastest operations: real() and conj().
 
     /**
      * Explicit benchmark without using a method reference.
      * This should run in the same time as {@link #real(ComplexNumbers, Blackhole)}.
      * This is commented out as it exists for reference purposes.
      *
      * @param numbers Numbers.
      * @param bh Data sink.
      */
     //@Benchmark
     public void real2(ComplexNumbers numbers, Blackhole bh) {
         final Complex[] z = numbers.getNumbers();
         for (int i = 0; i < z.length; i++) {
             bh.consume(z[i].real());
         }
     }
 
     /**
      * Explicit benchmark without using a method reference.
      * This should run in the same time as {@link #conj(ComplexNumbers, Blackhole)}.
      * This is commented out as it exists for reference purposes.
      *
      * @param numbers Numbers.
      * @param bh Data sink.
      */
     //@Benchmark
     public void conj2(ComplexNumbers numbers, Blackhole bh) {
         final Complex[] z = numbers.getNumbers();
         for (int i = 0; i < z.length; i++) {
             bh.consume(z[i].conj());
         }
     }
 
     /**
      * Baseline the JMH overhead for the loop execute to consume Complex objects.
      *
      * @param numbers Numbers.
      * @param bh Data sink.
      */
     @Benchmark
     public void baselineIdentity(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), ComplexPerformance::identity, bh);
     }
 
     /**
      * Baseline the creation of a copy complex number. This
      * measures the overhead of creation of new complex numbers including field access
      * to the real and imaginary parts.
      *
      * @param numbers Numbers.
      * @param bh Data sink.
      */
     @Benchmark
     public void baselineCopy(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), ComplexPerformance::copy, bh);
     }
 
     // Unary operations that a boolean
 
     @Benchmark
     public void isNaN(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::isNaN, bh);
     }
 
     @Benchmark
     public void isInfinite(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::isInfinite, bh);
     }
 
     @Benchmark
     public void isFinite(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::isFinite, bh);
     }
 
     // Unary operations that a double
 
     @Benchmark
     public void real(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::real, bh);
     }
 
     @Benchmark
     public void imag(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::imag, bh);
     }
 
     @Benchmark
     public void abs(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::abs, bh);
     }
 
     @Benchmark
     public void arg(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::arg, bh);
     }
 
     @Benchmark
     public void norm(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::norm, bh);
     }
 
     /**
      * This test demonstrates that the method used in abs() is not as fast as using square
      * root of the norm. The C99 standard for the abs() function requires over/underflow
      * protection in the intermediate computation and infinity edge case handling. This
      * has a performance overhead.
      *
      * @param numbers Numbers.
      * @param bh Data sink.
      */
     @Benchmark
     public void sqrtNorm(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), (ToDoubleFunction<Complex>) z -> Math.sqrt(z.norm()), bh);
     }
 
     /**
      * This test demonstrates that the {@link Math#hypot(double, double)} method
      * is not as fast as the custom implementation in abs().
      *
      * @param numbers Numbers.
      * @param bh Data sink.
      */
     @Benchmark
     public void absMathHypot(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), (ToDoubleFunction<Complex>) z -> Math.hypot(z.real(), z.imag()), bh);
     }
 
     // Unary operations that a complex number
 
     @Benchmark
     public void conj(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::conj, bh);
     }
 
     @Benchmark
     public void negate(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::negate, bh);
     }
 
     @Benchmark
     public void proj(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::proj, bh);
     }
 
     @Benchmark
     public void cos(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::cos, bh);
     }
 
     @Benchmark
     public void cosh(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::cosh, bh);
     }
 
     @Benchmark
     public void exp(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::exp, bh);
     }
 
     @Benchmark
     public void log(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::log, bh);
     }
 
     @Benchmark
     public void log10(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::log10, bh);
     }
 
     @Benchmark
     public void sin(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::sin, bh);
     }
 
     @Benchmark
     public void sinh(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::sinh, bh);
     }
 
     @Benchmark
     public void sqrt(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::sqrt, bh);
     }
 
     @Benchmark
     public void tan(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::tan, bh);
     }
 
     @Benchmark
     public void tanh(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::tanh, bh);
     }
 
     @Benchmark
     public void acos(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::acos, bh);
     }
 
     @Benchmark
     public void acosh(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::acosh, bh);
     }
 
     @Benchmark
     public void asin(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::asin, bh);
     }
 
     @Benchmark
     public void asinh(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::asinh, bh);
     }
 
     @Benchmark
     public void atan(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::atan, bh);
     }
 
     @Benchmark
     public void atanh(ComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), Complex::atanh, bh);
     }
 
     // Binary operations on two complex numbers.
 
     @Benchmark
     public void pow(TwoComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), numbers.getNumbers2(), Complex::pow, bh);
     }
 
     @Benchmark
     public void multiply(TwoComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), numbers.getNumbers2(), Complex::multiply, bh);
     }
 
     @Benchmark
     public void divide(TwoComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), numbers.getNumbers2(), Complex::divide, bh);
     }
 
     @Benchmark
     public void add(TwoComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), numbers.getNumbers2(), Complex::add, bh);
     }
 
     @Benchmark
     public void subtract(TwoComplexNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), numbers.getNumbers2(), Complex::subtract, bh);
     }
 
     // Binary operations on a complex and a real number.
     // These only benchmark methods on the real component as the
     // following are expected to be the same speed as the real-only operations
     // given the equivalent primitive operations:
     // - multiplyImaginary
     // - divideImaginary
     // - addImaginary
     // - subtractImaginary
     // - subtractFrom
     // - subtractFromImaginary
 
     @Benchmark
     public void powReal(ComplexAndRealNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), numbers.getNumbers2(), Complex::pow, bh);
     }
 
     @Benchmark
     public void multiplyReal(ComplexAndRealNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), numbers.getNumbers2(), Complex::multiply, bh);
     }
 
     @Benchmark
     public void divideReal(ComplexAndRealNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), numbers.getNumbers2(), Complex::divide, bh);
     }
 
     @Benchmark
     public void addReal(ComplexAndRealNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), numbers.getNumbers2(), Complex::add, bh);
     }
 
     @Benchmark
     public void subtractReal(ComplexAndRealNumbers numbers, Blackhole bh) {
         apply(numbers.getNumbers(), numbers.getNumbers2(), Complex::subtract, bh);
     }
 }