public void NLoptTutorialExample_TestCase_AnalyticSolution(NLoptAlgorithm nloptAlgorithm)
{
NLoptPtr ptr = new NLoptPtr(nloptAlgorithm, 2);
/* add and create boundary and nonlinear constraints: */
ptr.SetLowerBounds(new[] { Double.NegativeInfinity, 0.0 });
double a1 = 2.0;
double b1 = 0.0;
ptr.AddInequalityConstraint((n, x, grad, data) =>
{
if (grad != null)
{
grad[0] = 3.0 * a1 * (a1 * x[0] + b1) * (a1 * x[0] + b1);
grad[1] = -1.0;
}
return((a1 * x[0] + b1) * (a1 * x[0] + b1) * (a1 * x[0] + b1) - x[1]);
}, 1E-8);
double a2 = -1;
double b2 = 1.0;
var code = ptr.AddInequalityConstraint((n, x, grad, data) =>
{
if (grad != null)
{
grad[0] = 3.0 * a2 * (a2 * x[0] + b2) * (a2 * x[0] + b2);
grad[1] = -1.0;
}
return((a2 * x[0] + b2) * (a2 * x[0] + b2) * (a2 * x[0] + b2) - x[1]);
}, 1E-8);
ptr.SetFunction((n, x, grad, data) =>
{
if (grad != null)
{
grad[0] = 0.0;
grad[1] = 0.5 / Math.Sqrt(x[1]);
}
return(Math.Sqrt(x[1]));
});
ptr.TrySetRelativeXTolerance(1E-4);
var actualArgMin = new[] { 1.234, 5.678 };
double actualMinimum;
ptr.FindMinimum(actualArgMin, out actualMinimum);
double expectedMinimum = Math.Sqrt(8.0 / 27.0);
double expectedArgMin0 = 1.0 / 3.0;
double expectedArgMin1 = 8.0 / 27.0;
Assert.That(actualMinimum, Is.EqualTo(expectedMinimum).Within(1E-3));
Assert.That(actualArgMin[0], Is.EqualTo(expectedArgMin0).Within(1E-3));
Assert.That(actualArgMin[1], Is.EqualTo(expectedArgMin1).Within(1E-3));
}
/// <summary>Sets a specific subsidiary (local) optimizer.
/// </summary>
/// <param name="nloptLocalOptimizer">The local optimizer.</param>
/// <returns></returns>
/// <exception cref="ArgumentNullException">Thrown, if <paramref name="nloptLocalOptimizer"/> is <c>null</c>.</exception>
public NLoptResultCode SetLocalOptimizer(NLoptPtr nloptLocalOptimizer)
{
if (nloptLocalOptimizer == null)
{
throw new ArgumentNullException(nameof(nloptLocalOptimizer));
}
if (m_NLopPtr == IntPtr.Zero)
{
throw new ObjectDisposedException("NLoptPtr");
}
return(nlopt_set_local_optimizer((IntPtr)m_NLopPtr, (IntPtr)nloptLocalOptimizer.m_NLopPtr));
}
/// <summary>Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
/// </summary>
public void Dispose()
{
m_NLoptPtr.Dispose();
m_NLoptPtr = null;
if (m_LoggerStream != null)
{
m_LoggerStreamGCHandle.Free();
// m_LoggerStream.Dispose();
m_LoggerStream = null;
}
}
/// <summary>Initializes a new instance of the <see cref="NLoptMultiDimOptimizer" /> class.
/// </summary>
/// <param name="algorithm">A value indicating the specific NLopt algorithm.</param>
/// <param name="abortCondition">The abort (stopping) condition of the NLopt algorithm.</param>
/// <param name="nloptPtrAdjustment">An optional delegate which will be called in the <c>Create</c> methods for <see cref="IMultiDimOptimizerAlgorithm"/> objects that allows individual adjustments of the internal <see cref="NLoptPtr"/> representation.</param>
/// <param name="loggerStreamFactory">A factory for <see cref="ILoggerStream"/> objects, i.e. for a logging. Each <see cref="IMultiDimOptimizerAlgorithm"/> object will track the function values in the specified logger.</param>
/// <remarks>One can use <paramref name="nloptPtrAdjustment"/> to change the Initial step size, initial "population" of random points, set Local/subsidiary optimization algorithm etc. See
/// the documentation of the NLopt library http://ab-initio.mit.edu/wiki/index.php/NLopt for further details.</remarks>
public NLoptMultiDimOptimizer(NLoptAlgorithm algorithm, NLoptAbortCondition abortCondition, Action <NLoptPtr> nloptPtrAdjustment = null, Func <IMultiDimOptimizerAlgorithm, ILogger> loggerStreamFactory = null)
{
Algorithm = algorithm;
Configuration = NLoptConfiguration.Create(algorithm);
if (abortCondition == null)
{
throw new ArgumentNullException("abortCondition");
}
AbortCondition = abortCondition;
m_LongName = new IdentifierString(NLoptPtr.GetName(algorithm));
m_Name = new IdentifierString(algorithm.ToFormatString(EnumStringRepresentationUsage.StringAttribute));
Constraint = new NLoptConstraintFactory(this);
Function = new NLoptFunctionFactory(this);
m_nloptPtrAdjustment = nloptPtrAdjustment;
m_LoggerStreamFactory = loggerStreamFactory;
}
public void NLoptPRAXIS_TestCase_AnalyticMinimum()
{
NLoptPtr ptr = new NLoptPtr(NLoptAlgorithm.LN_PRAXIS, 2);
ptr.TrySetAbsoluteFValueTolerance(1E-6);
ptr.TrySetRelativeFValueTolerance(1E-6);
ptr.TrySetAbsoluteXTolerance(1E-6);
ptr.TrySetRelativeXTolerance(1E-6);
ptr.SetFunction((n, x, gradient, data) => { return(x[0] * x[0] + x[1] * x[1] + 1.123); });
double[] argMin = new double[2] {
1.0, 4.8
};
double actual;
var code = ptr.FindMinimum(argMin, out actual);
double expected = 1.123;
Assert.That(actual, Is.EqualTo(expected).Within(1E-6));
}
/// <summary>Initializes a new instance of the <see cref="Wrapper" /> class.
/// </summary>
/// <param name="nloptMultiDimOptimizer">The <see cref="NLoptMultiDimOptimizer"/> object that has been used to create the current instance.</param>
/// <param name="dimension">The dimension.</param>
public Wrapper(NLoptMultiDimOptimizer nloptMultiDimOptimizer, int dimension)
{
m_Factory = nloptMultiDimOptimizer;
m_NLoptPtr = new NLoptPtr(nloptMultiDimOptimizer.Algorithm, dimension);
// check whether the algorithm allows an unconstraint feasible region:
if ((nloptMultiDimOptimizer.Configuration.BoxConstraintRequirement == NLoptBoundConstraintRequirement.Required) ||
(nloptMultiDimOptimizer.Configuration.NonlinearConstraintRequirement.HasFlag(NLoptNonlinearConstraintRequirement.RequiredInequalityConstraints)) ||
(nloptMultiDimOptimizer.Configuration.NonlinearConstraintRequirement.HasFlag(NLoptNonlinearConstraintRequirement.RequiredEqualityConstraints)))
{
throw new InvalidOperationException("The optimizer does not support unconstraint feasible region.");
}
nloptMultiDimOptimizer.AbortCondition.ApplyTo(m_NLoptPtr);
if (nloptMultiDimOptimizer.m_nloptPtrAdjustment != null) // apply some optional individual adjustments
{
nloptMultiDimOptimizer.m_nloptPtrAdjustment(m_NLoptPtr);
}
if (nloptMultiDimOptimizer.m_LoggerStreamFactory != null)
{
m_LoggerStream = nloptMultiDimOptimizer.m_LoggerStreamFactory(this);
m_LoggerStreamGCHandle = GCHandle.Alloc(m_LoggerStream);
}
}
/// <summary>Initializes a new instance of the <see cref="Wrapper" /> class.
/// </summary>
/// <param name="nloptMultiDimOptimizer">The <see cref="NLoptMultiDimOptimizer"/> object that has been used to create the current instance.</param>
/// <param name="dimension">The dimension.</param>
/// <param name="nloptConstraints">The constraints of the optimization algorithm in its <see cref="NLoptConstraint"/> representation.</param>
internal Wrapper(NLoptMultiDimOptimizer nloptMultiDimOptimizer, int dimension, IEnumerable <NLoptConstraint> nloptConstraints)
{
m_Factory = nloptMultiDimOptimizer;
m_NLoptPtr = new NLoptPtr(nloptMultiDimOptimizer.Algorithm, dimension);
nloptMultiDimOptimizer.AbortCondition.ApplyTo(m_NLoptPtr);
foreach (var constraint in nloptConstraints)
{
if (constraint.Dimension != dimension)
{
throw new ArgumentException(String.Format(ExceptionMessages.ArgumentHasWrongDimension, constraint), nameof(nloptConstraints));
}
constraint.ApplyTo(m_NLoptPtr);
}
if (nloptMultiDimOptimizer.m_nloptPtrAdjustment != null) // apply some optional individual adjustments
{
nloptMultiDimOptimizer.m_nloptPtrAdjustment(m_NLoptPtr);
}
if (nloptMultiDimOptimizer.m_LoggerStreamFactory != null)
{
m_LoggerStream = nloptMultiDimOptimizer.m_LoggerStreamFactory(this);
m_LoggerStreamGCHandle = GCHandle.Alloc(m_LoggerStream);
}
}
/// <summary>Applies the constraints represented by the current instance to a specific NLopt algorithm in its <see cref="NLoptPtr"/> representation.
/// </summary>
/// <param name="nloptPtr">The NLopt algorithm to apply the abort (stopping) condition in its <see cref="NLoptPtr"/> representation.</param>
internal void ApplyTo(NLoptPtr nloptPtr)
{
m_ApplyToNLoptPtr(nloptPtr);
}
/// <summary>Applies the abort (stopping) condition represented by the current instance to a specific NLopt algorithm in its <see cref="NLoptPtr"/> representation.
/// </summary>
/// <param name="nloptPtr">The NLopt algorithm in its <see cref="NLoptPtr"/> representation to apply the abort (stopping) condition.</param>
public void ApplyTo(NLoptPtr nloptPtr)
{
m_ApplyToNLoptPtr(nloptPtr);
}
