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2022-10-08 afedb8fd4e17a5a911deee3dae04a10a93e6a39a
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// <copyright file="ObjectiveFunction.cs" company="Math.NET">
// Math.NET Numerics, part of the Math.NET Project
// http://numerics.mathdotnet.com
// http://github.com/mathnet/mathnet-numerics
//
// Copyright (c) 2009-2017 Math.NET
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without
// restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
// </copyright>
 
using System;
using IStation.Numerics.LinearAlgebra;
using IStation.Numerics.Optimization.ObjectiveFunctions;
 
namespace IStation.Numerics.Optimization
{
    public static class ObjectiveFunction
    {
        /// <summary>
        /// Objective function where neither Gradient nor Hessian is available.
        /// </summary>
        public static IObjectiveFunction Value(Func<Vector<double>, double> function)
        {
            return new ValueObjectiveFunction(function);
        }
 
        /// <summary>
        /// Objective function where the Gradient is available. Greedy evaluation.
        /// </summary>
        public static IObjectiveFunction Gradient(Func<Vector<double>, Tuple<double, Vector<double>>> function)
        {
            return new GradientObjectiveFunction(function);
        }
 
        /// <summary>
        /// Objective function where the Gradient is available. Lazy evaluation.
        /// </summary>
        public static IObjectiveFunction Gradient(Func<Vector<double>, double> function, Func<Vector<double>, Vector<double>> gradient)
        {
            return new LazyObjectiveFunction(function, gradient: gradient);
        }
 
        /// <summary>
        /// Objective function where the Hessian is available. Greedy evaluation.
        /// </summary>
        public static IObjectiveFunction Hessian(Func<Vector<double>, Tuple<double, Matrix<double>>> function)
        {
            return new HessianObjectiveFunction(function);
        }
 
        /// <summary>
        /// Objective function where the Hessian is available. Lazy evaluation.
        /// </summary>
        public static IObjectiveFunction Hessian(Func<Vector<double>, double> function, Func<Vector<double>, Matrix<double>> hessian)
        {
            return new LazyObjectiveFunction(function, hessian: hessian);
        }
 
        /// <summary>
        /// Objective function where both Gradient and Hessian are available. Greedy evaluation.
        /// </summary>
        public static IObjectiveFunction GradientHessian(Func<Vector<double>, Tuple<double, Vector<double>, Matrix<double>>> function)
        {
            return new GradientHessianObjectiveFunction(function);
        }
 
        /// <summary>
        /// Objective function where both Gradient and Hessian are available. Lazy evaluation.
        /// </summary>
        public static IObjectiveFunction GradientHessian(Func<Vector<double>, double> function, Func<Vector<double>, Vector<double>> gradient, Func<Vector<double>, Matrix<double>> hessian)
        {
            return new LazyObjectiveFunction(function, gradient: gradient, hessian: hessian);
        }
 
        /// <summary>
        /// Objective function where neither first nor second derivative is available.
        /// </summary>
        public static IScalarObjectiveFunction ScalarValue(Func<double, double> function)
        {
            return new ScalarValueObjectiveFunction(function);
        }
 
        /// <summary>
        /// Objective function where the first derivative is available.
        /// </summary>
        public static IScalarObjectiveFunction ScalarDerivative(Func<double, double> function, Func<double, double> derivative)
        {
            return new ScalarObjectiveFunction(function, derivative);
        }
 
        /// <summary>
        /// Objective function where the first and second derivatives are available.
        /// </summary>
        public static IScalarObjectiveFunction ScalarSecondDerivative(Func<double, double> function, Func<double, double> derivative, Func<double,double> secondDerivative)
        {
            return new ScalarObjectiveFunction(function, derivative, secondDerivative);
        }
 
        /// <summary>
        /// objective model with a user supplied jacobian for non-linear least squares regression.
        /// </summary>
        public static IObjectiveModel NonlinearModel(Func<Vector<double>, Vector<double>, Vector<double>> function,
            Func<Vector<double>, Vector<double>, Matrix<double>> derivatives,
            Vector<double> observedX, Vector<double> observedY, Vector<double> weight = null)
        {
            var objective = new NonlinearObjectiveFunction(function, derivatives);
            objective.SetObserved(observedX, observedY, weight);
            return objective;
        }
 
        /// <summary>
        /// Objective model for non-linear least squares regression.
        /// </summary>
        public static IObjectiveModel NonlinearModel(Func<Vector<double>, Vector<double>, Vector<double>> function,
            Vector<double> observedX, Vector<double> observedY, Vector<double> weight = null,
            int accuracyOrder = 2)
        {
            var objective = new NonlinearObjectiveFunction(function, accuracyOrder: accuracyOrder);
            objective.SetObserved(observedX, observedY, weight);
            return objective;
        }
 
        /// <summary>
        /// Objective model with a user supplied jacobian for non-linear least squares regression.
        /// </summary>
        public static IObjectiveModel NonlinearModel(Func<Vector<double>, double, double> function,
            Func<Vector<double>, double, Vector<double>> derivatives,
            Vector<double> observedX, Vector<double> observedY, Vector<double> weight = null)
        {
            Vector<double> func(Vector<double> point, Vector<double> x)
            {
                var functionValues = CreateVector.Dense<double>(x.Count);
                for (int i = 0; i < x.Count; i++)
                {
                    functionValues[i] = function(point, x[i]);
                }
 
                return functionValues;
            }
 
            Matrix<double> prime(Vector<double> point, Vector<double> x)
            {
                var derivativeValues = CreateMatrix.Dense<double>(x.Count, point.Count);
                for (int i = 0; i < x.Count; i++)
                {
                    derivativeValues.SetRow(i, derivatives(point, x[i]));
                }
 
                return derivativeValues;
            }
 
            var objective = new NonlinearObjectiveFunction(func, prime);
            objective.SetObserved(observedX, observedY, weight);
            return objective;
        }
 
        /// <summary>
        /// Objective model for non-linear least squares regression.
        /// </summary>
        public static IObjectiveModel NonlinearModel(Func<Vector<double>, double, double> function,
            Vector<double> observedX, Vector<double> observedY, Vector<double> weight = null,
            int accuracyOrder = 2)
        {
            Vector<double> func(Vector<double> point, Vector<double> x)
            {
                var functionValues = CreateVector.Dense<double>(x.Count);
                for (int i = 0; i < x.Count; i++)
                {
                    functionValues[i] = function(point, x[i]);
                }
 
                return functionValues;
            }
 
            var objective = new NonlinearObjectiveFunction(func, accuracyOrder: accuracyOrder);
            objective.SetObserved(observedX, observedY, weight);
            return objective;
        }
 
        /// <summary>
        /// Objective function with a user supplied jacobian for nonlinear least squares regression.
        /// </summary>
        public static IObjectiveFunction NonlinearFunction(Func<Vector<double>, Vector<double>, Vector<double>> function,
            Func<Vector<double>, Vector<double>, Matrix<double>> derivatives,
            Vector<double> observedX, Vector<double> observedY, Vector<double> weight = null)
        {
            var objective = new NonlinearObjectiveFunction(function, derivatives);
            objective.SetObserved(observedX, observedY, weight);
            return objective.ToObjectiveFunction();
        }
 
        /// <summary>
        /// Objective function for nonlinear least squares regression.
        /// The numerical jacobian with accuracy order is used.
        /// </summary>
        public static IObjectiveFunction NonlinearFunction(Func<Vector<double>, Vector<double>, Vector<double>> function,
            Vector<double> observedX, Vector<double> observedY, Vector<double> weight = null,
            int accuracyOrder = 2)
        {
            var objective = new NonlinearObjectiveFunction(function, null, accuracyOrder: accuracyOrder);
            objective.SetObserved(observedX, observedY, weight);
            return objective.ToObjectiveFunction();
        }
    }
}