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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
//
// This program solves the "lorenz" equations using Runge-Kutta 4
using Microsoft.Xunit.Performance;
using System;
using System.Runtime.CompilerServices;
using Xunit;
[assembly: OptimizeForBenchmarks]
[assembly: MeasureInstructionsRetired]
namespace Benchstone.BenchF
{
public static class Lorenz
{
#if DEBUG
public const int Iterations = 1;
#else
public const int Iterations = 8000000;
#endif
private static double s_t = 0.0;
private static double s_x = 5.0;
private static double s_y = 2.0;
private static double s_z = 27.0;
private static int s_nsteps = Iterations;
private static double s_h = -1.0;
private static int s_printDerivative = -1;
[MethodImpl(MethodImplOptions.NoInlining)]
private static bool Bench()
{
double k1, k2, k3, k4;
double l1, l2, l3, l4;
double m1, m2, m3, m4;
double hdiv2, hdiv6;
int i;
if (s_h < 0.0)
{
s_h = 20.0 / (double)s_nsteps;
}
if (s_printDerivative < 0)
{
s_printDerivative = s_nsteps;
}
hdiv2 = s_h / 2.0;
hdiv6 = s_h / 6.0;
for (i = 0; i < s_nsteps; ++i)
{
double t_arg, x_arg, y_arg, z_arg;
k1 = F(s_t, s_x, s_y, s_z);
l1 = G(s_t, s_x, s_y, s_z);
m1 = H(s_t, s_x, s_y, s_z);
t_arg = s_t + hdiv2;
x_arg = s_x + hdiv2 * k1;
y_arg = s_y + hdiv2 * l1;
z_arg = s_z + hdiv2 * m1;
k2 = F(t_arg, x_arg, y_arg, z_arg);
l2 = G(t_arg, x_arg, y_arg, z_arg);
m2 = H(t_arg, x_arg, y_arg, z_arg);
x_arg = s_x + hdiv2 * k2;
y_arg = s_y + hdiv2 * l2;
z_arg = s_z + hdiv2 * m2;
k3 = F(t_arg, x_arg, y_arg, z_arg);
l3 = G(t_arg, x_arg, y_arg, z_arg);
m3 = H(t_arg, x_arg, y_arg, z_arg);
t_arg = s_t + s_h;
x_arg = s_x + s_h * k3;
y_arg = s_y + s_h * l3;
z_arg = s_z + s_h * m3;
k4 = F(t_arg, x_arg, y_arg, z_arg);
l4 = G(t_arg, x_arg, y_arg, z_arg);
m4 = H(t_arg, x_arg, y_arg, z_arg);
s_x = s_x + hdiv6 * (k1 + 2.0 * k2 + 2.0 * k3 + k4);
s_y = s_y + hdiv6 * (l1 + 2.0 * l2 + 2.0 * l3 + l4);
s_z = s_z + hdiv6 * (m1 + 2.0 * m2 + 2.0 * m3 + m4);
s_t = t_arg;
}
return true;
}
private static double F(double t, double x, double y, double z)
{
return (10.0 * (y - x));
}
private static double G(double t, double x, double y, double z)
{
return (x * (28.0 - z) - y);
}
private static double H(double t, double x, double y, double z)
{
return (x * y - (8.0 * z) / 3.0);
}
[Benchmark]
public static void Test()
{
foreach (var iteration in Benchmark.Iterations)
{
using (iteration.StartMeasurement())
{
Bench();
}
}
}
private static bool TestBase()
{
bool result = Bench();
return result;
}
public static int Main()
{
bool result = TestBase();
return (result ? 100 : -1);
}
}
}
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