#region License Information
/* HeuristicLab
* Copyright (C) 2002-2018 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
*
* This file is part of HeuristicLab.
*
* HeuristicLab is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* HeuristicLab is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with HeuristicLab. If not, see .
*/
#endregion
using System;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Data;
using HeuristicLab.Parameters;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
namespace HeuristicLab.Optimization.Operators {
///
/// Modifies a value by exponentially.
///
[Item("GeneralizedExponentialDiscreteDoubleValueModifier", @"Modifies the value exponentially.
The base is a standardized exponential function with exponent `Base`
that is then transformed to pass through the startValue at the startIndex
and through the endValue at the endIndex.
For a slow change initially use a value > 1 for `Base`.
For a steep change initially use a value < 1 for `Base`.
Negative slopes are automatically generated if the start value is greater than the end value.
If you use `base`=1 you will get a linear interpolation.")]
[StorableClass]
public class GeneralizedExponentialDiscreteDoubleValueModifier : DiscreteDoubleValueModifier {
protected ValueLookupParameter BaseParameter {
get { return (ValueLookupParameter) Parameters["Base"]; }
}
private double Base { get { return BaseParameter.Value.Value; } }
[StorableConstructor]
protected GeneralizedExponentialDiscreteDoubleValueModifier(bool deserializing) : base(deserializing) { }
protected GeneralizedExponentialDiscreteDoubleValueModifier(GeneralizedExponentialDiscreteDoubleValueModifier original, Cloner cloner) : base(original, cloner) { }
public GeneralizedExponentialDiscreteDoubleValueModifier() {
Parameters.Add(new ValueLookupParameter("Base", "Base of the exponential function. Must be > 0. If > 1 steep in the end, if < 1 steep at the start, if == 1 linear interpolation.", new DoubleValue(0.00001)));
}
public override IDeepCloneable Clone(Cloner cloner) {
return new GeneralizedExponentialDiscreteDoubleValueModifier(this, cloner);
}
///
/// Calculates a new value based on exponential decay or growth.
///
/// Thrown if Base <= 0.
/// The previous value.
/// The initial value.
/// The final value.
/// The current index.
/// The initial index.
/// The final index.
/// The new value.
protected override double Modify(double value, double startValue, double endValue, int index, int startIndex, int endIndex) {
if (Base <= 0)
throw new ArgumentException("Base must be > 0.");
if (Base == 1.0)
return startValue + (endValue - startValue)*(index - startIndex)/(endIndex - startIndex);
return startValue + (endValue - startValue)*(Math.Pow(Base, 1.0*(index-startIndex)/(endIndex-startIndex)) - 1)/(Base - 1);
}
}
}