public class FuncBuilderHelper
    {
        public static IList<string> FuncList { get; }= new List<string>()
            {
                "sin" ,
                "cos",
                "tan",
                "cotan",
                "acos",
                "asin",
                "atan"
            };
        public static Func<double,double,double> GenerateFunc(string funcTitle,double[] pars)
        {
            Func<double, double, double> result = null;
            switch (funcTitle)
            {
                case "sin":
                    result = (x, y) => pars[0] / pars[1] * Math.Sin(x * pars[2] / pars[3]) + x * pars[4] / pars[5];
                    break;
                case "cos":
                    result = (x, y) => pars[0] / pars[1] * Math.Cos(x * pars[2] / pars[3]) + x * pars[4] / pars[5];
                    break;
                case "tan":
                    result = (x, y) => pars[0] / pars[1] * Math.Tan(x * pars[2] / pars[3]) + x * pars[4] / pars[5];
                    break;
                case "cotan":
                    result = (x, y) => pars[0] / pars[1] / Math.Tan(x * pars[2] / pars[3]) + x * pars[4] / pars[5];
                    break;
                case "acos":
                    result = (x, y) => pars[0] / pars[1] * Math.Acos(x * pars[2] / pars[3]) + x * pars[4] / pars[5];
                    break;
                case "asin":
                    result = (x, y) => pars[0] / pars[1] * Math.Asin(x * pars[2] / pars[3]) + x * pars[4] / pars[5];
                    break;
                case "atan":
                    result = (x, y) => pars[0] / pars[1] * Math.Atan(x * pars[2] / pars[3]) + x * pars[4] / pars[5];
                    break;
                default:
                    break;
            }
            return result;
        }
    }