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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.
//
// The Bisect algorithm adapted from Conte and de Boor
using Microsoft.Xunit.Performance;
using System;
using System.Runtime.CompilerServices;
using Xunit;
[assembly: OptimizeForBenchmarks]
namespace Benchstone.BenchF
{
public static class Bisect
{
#if DEBUG
public const int Iterations = 1;
#else
public const int Iterations = 400000;
#endif
public static volatile object VolatileObject;
[MethodImpl(MethodImplOptions.NoInlining)]
private static void Escape(object obj)
{
VolatileObject = obj;
}
[MethodImpl(MethodImplOptions.NoInlining)]
private static bool Bench()
{
int idbg, iflag;
double a, b, error, p1, xi;
iflag = 0;
error = 0.0;
xi = 0.0;
idbg = 0;
for (int i = 1; i <= Iterations; i++)
{
for (int j = 1; j <= 10; j++)
{
a = 1.0;
b = 2.0;
p1 = 0.000001;
Inner(ref a, ref b, ref p1, out iflag);
if (iflag > 1)
{
goto L999;
}
xi = (a + b) / 2.0;
if (a > b)
{
error = (a - b) / 2.0;
}
else
{
error = (b - a) / 2.0;
}
if (idbg != 0)
{
System.Console.WriteLine(" the root is {0:E} plus/minus {1:E}\n", xi, error);
}
}
}
L999:
{
}
// Escape iflag, error, xi so that they appear live
Escape(iflag);
Escape(error);
Escape(xi);
return true;
}
private static double FF(double x)
{
return ((-1.0 - (x * (1.0 - (x * x)))));
}
private static void Inner(ref double a, ref double b, ref double xtol, out int iflag)
{
double fa, error;
double xm, fm;
iflag = 0;
fa = FF(a);
/* check for sign change */
if (((fa) * FF(b)) < 0.0)
{
goto L5;
}
iflag = 2;
goto L99;
L5:
{
error = System.Math.Abs(b - a);
}
L6:
error = error / 2.0;
/* check for sufficiently small interval */
if (error < xtol)
{
goto L99;
}
xm = (a + b) / 2.0;
/* check for unreasonable error requirement */
if (xm + error == xm)
{
goto L20;
}
fm = FF(xm);
/* change to new interval */
if (fa * fm < 0.0)
{
goto L9;
}
a = xm;
fa = fm;
goto L6;
L9:
b = xm;
goto L6;
L20:
iflag = 1;
L99:
{
}
}
[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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