求解器得到决策中设置的最小值

Question

我是运行一个代码，需要计算构成动物食品的成分的适当百分比。为了做到这一点，我正在使用 MS solver foundation。我将模型设置为传递成分和营养素的最小值和最大值（成分百分比会或多或少地影响营养素）。我需要构成动物食品的最便宜（最小化）成本。这是我的代码。

  private Solution FormularRacao()
    {
        var ingredientesRacao = _formulacaoRacao.CarregarIngredientesNutrientesFormulacao(true);
        var nutrientes = _formulacaoRacao.CarregarIngredientesNutrientesFormulacao(false);
        var formulacao = _formulacaoRacao.CarregarFormulacao();

        SolverContext context = SolverContext.GetContext();
        context.ClearModel();

        Model model = context.CreateModel();

        var objetivo = new SumTermBuilder(ingredientesRacao.Count);
        var totalIngrediente = new SumTermBuilder(ingredientesRacao.Count);

        List<SumTermBuilder> listaTotalNutriente = new List<SumTermBuilder>();

        //Set decisions
        foreach (var item in ingredientesRacao)
        {
            item.Nome = TratarNome(item.Nome);

            Decision d = new Decision(Domain.RealRange(Convert.ToDouble(item.Minimo), Convert.ToDouble(item.Maximo)), "d_" + item.Nome);

            model.AddDecision(d);

            objetivo.Add(Model.Product(d, Convert.ToDouble(item.Custo)));
            totalIngrediente.Add(d);
            listaTotalNutriente.Add(new SumTermBuilder(nutrientes.Count));
        }

        var SomaIngrediente = totalIngrediente.ToTerm();

        //sum of decisions values must be equal 100
        model.AddConstraint("c_totalIngrediente", SomaIngrediente == 100);

        //totalIngrediente;
        model.AddGoal("racao", GoalKind.Minimize, objetivo.ToTerm());

        int indexIngrediente = 0;
        int indexNutriente = 0;

        //each ingredient contributes with nutrients
        //each nutrient has a min and max set            
        foreach (var ingredienteRacao in ingredientesRacao)
        {
            Ingrediente ingrediente = _formulacaoRacao.CarregarIngrediente(ingredienteRacao.Id);
            indexNutriente = 0;
            ingredienteRacao.Nome = TratarNome(ingredienteRacao.Nome);
            Decision d = model.Decisions.First(x => x.Name == "d_" + ingredienteRacao.Nome);

            foreach (var nutriente in nutrientes)
            {
                var valor = new object();

                if (nutriente.AminoacidoDigestivo.Equals("S"))
                {
                    var aminoacidoDigestivo = _formulacaoRacao.CarregarAminoacidoDigestivo(ingredienteRacao.Id);
                    valor = aminoacidoDigestivo.GetType().GetProperty(nutriente.Nome).GetValue(aminoacidoDigestivo, null);
                }
                else
                {
                    nutriente.Nome = TratarNomeNutriente(nutriente.Nome);
                    valor = ingrediente.GetType().GetProperty(nutriente.Nome).GetValue(ingrediente, null);
                }

                var proporcaoNutriente = Convert.ToDouble(valor.ToString()) * d;

                listaTotalNutriente[indexNutriente].Add(proporcaoNutriente / 100);

                if (indexIngrediente == ingredientesRacao.Count - 1) //last iteration
                {
                    var totalNutriente = listaTotalNutriente[indexNutriente].ToTerm();
                    if (nutriente.Minimo == nutriente.Maximo)
                       model.AddConstraint("c_" + nutriente.Nome, totalNutriente == Convert.ToDouble(nutriente.Maximo));                        
                    else
                        model.AddConstraint("c" + nutriente.Nome, Convert.ToDouble(nutriente.Minimo) <= totalNutriente <= Convert.ToDouble(nutriente.Maximo));                        
                }

                indexNutriente++;
            }
            indexIngrediente++;
        }            

        //saves the model
        TextWriter tw = new StreamWriter("Path\file.oml");
        context.SaveModel(FileFormat.OML, tw);
        tw.Close();

        //Imprime o modelo
        TextWriter txt = new StreamWriter("Path\file.txt");
        foreach (var item in model.Constraints.ToList())
        {
            txt.WriteLine(item.Name + ":  " + item.Expression);
            txt.WriteLine();
        }
        txt.Close();

        Solution solution = context.Solve();

        return solution;
    }

结果我得到了它所设置的决定的最小值，这意味着没有找到解决方案。我的问题是：为什么求解器考虑决策中设置的最小值而不是为每个决策计算适当的值？

Answer 1

这是我建模时的错误。代码运行良好。但它通过创建一个 txt 文件并向其添加所有约束确实帮助我解决了问题，因此我可以仔细检查我设置的约束并创建一个模型文件 (oml) 并将其导入 Excel这样我就可以检查所有设置的约束来求解模型。我的问题中的代码已更新，因此如果您需要，可以查看如何创建 txt 和 oml 文件。

求解器得到决策中设置的最小值

solver gets the minimum value set in decision

c#

solver

winforms

simplex-algorithm