Complex Division Benchmark

Program.cs

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;
using System;
using System.Numerics;

namespace ComplexBenchmark
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var summary = BenchmarkRunner.Run<ComplexBenchmark>();
        }
    }

    public class ComplexBenchmark
    {
        private readonly (double, Complex)[] values;

        public ComplexBenchmark()
        {
            values = new[]
            {
                (15.61234, new Complex(15, 10)),
                (0.1234, new Complex(1, 255)),
                (0.899, new Complex(642123.6, 1)),
                (5, new Complex(29, 33)),
            };
        }

        [Benchmark]
        public void Original()
        {
            foreach ((double, Complex) value in values)
            {
                var a = DivideOriginal(value.Item1, value.Item2);
            }
        }

        [Benchmark]
        public void Simplified()
        {
            foreach ((double, Complex) value in values)
            {
                var a = DivideSimplified(value.Item1, value.Item2);
            }
        }


        public static Complex DivideOriginal(double left, Complex right)
        {
            // Division : Smith's formula.
            double a = left;
            double c = right.Real;
            double d = right.Imaginary;

            if (Math.Abs(d) < Math.Abs(c))
            {
                double doc = d / c;
                return new Complex(a / (c + d * doc), (-a * doc) / (c + d * doc));
            }
            else
            {
                double cod = c / d;
                return new Complex(a * cod / (d + c * cod), -a / (d + c * cod));
            }
        }

        public static Complex DivideSimplified(double left, Complex right)
        {
            //  a        a     c-di    ac      -ad
            // ----   = ---- X ---- = ----- + ---- i
            // c+di     c+di   c-di   cc+dd   cc+dd
            double a = left;
            double c = right.Real;
            double d = right.Imaginary;

            double divisor = (c * c) + (d * d);
            return new Complex((a * c) / divisor, -(a * d) / divisor);
        }
    }
}