Math.NET Numerics
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using System;
using MathNet.Numerics.LinearAlgebra.Double;
using MathNet.Numerics.Optimization;
using NUnit.Framework;
namespace MathNet.Numerics.UnitTests.OptimizationTests
{
[TestFixture]
public class TestBfgsMinimizer
{
[Test]
public void FindMinimum_Rosenbrock_Easy()
{
var obj = ObjectiveFunction.Gradient(RosenbrockFunction.Value, RosenbrockFunction.Gradient);
var solver = new BfgsMinimizer(1e-5, 1e-5, 1000);
var result = solver.FindMinimum(obj, new DenseVector(new[] { 1.2, 1.2 }));
Assert.That(Math.Abs(result.MinimizingPoint[0] - RosenbrockFunction.Minimum[0]), Is.LessThan(1e-3));
Assert.That(Math.Abs(result.MinimizingPoint[1] - RosenbrockFunction.Minimum[1]), Is.LessThan(1e-3));
}
[Test]
public void FindMinimum_Rosenbrock_Hard()
{
var obj = ObjectiveFunction.Gradient(RosenbrockFunction.Value, RosenbrockFunction.Gradient);
var solver = new BfgsMinimizer(1e-5, 1e-5, 1000);
var result = solver.FindMinimum(obj, new DenseVector(new[] { -1.2, 1.0 }));
Assert.That(Math.Abs(result.MinimizingPoint[0] - RosenbrockFunction.Minimum[0]), Is.LessThan(1e-3));
Assert.That(Math.Abs(result.MinimizingPoint[1] - RosenbrockFunction.Minimum[1]), Is.LessThan(1e-3));
}
[Test]
public void FindMinimum_Rosenbrock_Overton()
{
var obj = ObjectiveFunction.Gradient(RosenbrockFunction.Value, RosenbrockFunction.Gradient);
var solver = new BfgsMinimizer(1e-5, 1e-5, 1000);
var result = solver.FindMinimum(obj, new DenseVector(new[] { -0.9, -0.5 }));
Assert.That(Math.Abs(result.MinimizingPoint[0] - RosenbrockFunction.Minimum[0]), Is.LessThan(1e-3));
Assert.That(Math.Abs(result.MinimizingPoint[1] - RosenbrockFunction.Minimum[1]), Is.LessThan(1e-3));
}
[Test]
public void FindMinimum_BigRosenbrock_Easy()
{
var obj = ObjectiveFunction.Gradient(BigRosenbrockFunction.Value, BigRosenbrockFunction.Gradient);
var solver = new BfgsMinimizer(1e-10, 1e-5, 1000);
var result = solver.FindMinimum(obj, new DenseVector(new[] { 1.2*100.0, 1.2*100.0 }));
Assert.That(Math.Abs(result.MinimizingPoint[0] - BigRosenbrockFunction.Minimum[0]), Is.LessThan(1e-3));
Assert.That(Math.Abs(result.MinimizingPoint[1] - BigRosenbrockFunction.Minimum[1]), Is.LessThan(1e-3));
}
[Test]
public void FindMinimum_BigRosenbrock_Hard()
{
var obj = ObjectiveFunction.Gradient(BigRosenbrockFunction.Value, BigRosenbrockFunction.Gradient);
var solver = new BfgsMinimizer(1e-5, 1e-5, 1000);
var result = solver.FindMinimum(obj, new DenseVector(new[] { -1.2*100.0, 1.0*100.0 }));
Assert.That(Math.Abs(result.MinimizingPoint[0] - BigRosenbrockFunction.Minimum[0]), Is.LessThan(1e-3));
Assert.That(Math.Abs(result.MinimizingPoint[1] - BigRosenbrockFunction.Minimum[1]), Is.LessThan(1e-3));
}
[Test]
public void FindMinimum_BigRosenbrock_Overton()
{
var obj = ObjectiveFunction.Gradient(BigRosenbrockFunction.Value, BigRosenbrockFunction.Gradient);
var solver = new BfgsMinimizer(1e-5, 1e-5, 1000);
var result = solver.FindMinimum(obj, new DenseVector(new[] { -0.9*100.0, -0.5*100.0 }));
Assert.That(Math.Abs(result.MinimizingPoint[0] - BigRosenbrockFunction.Minimum[0]), Is.LessThan(1e-3));
Assert.That(Math.Abs(result.MinimizingPoint[1] - BigRosenbrockFunction.Minimum[1]), Is.LessThan(1e-3));
}
}
}