//using NPOI.SS.Formula.Functions;
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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Numerics;
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using System.Text;
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using System.Threading.Tasks;
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namespace Yw.WinFrmUI.Q3d
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{
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public class MathSolver
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{
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static double ErrNum = -1;
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public static List<double> Solve(double a, double b, double c)
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{
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// 求解二次方程 ax^2 + bx + c = 0
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double delta = b * b - 4 * a * c;
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if (delta >= 0)
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{
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double x1 = (-b + Math.Sqrt(delta)) / (2 * a);
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double x2 = (-b - Math.Sqrt(delta)) / (2 * a);
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return new List<double> { x1, x2 };
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}
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else
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{
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return null;
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}
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}
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public static List<double> Solve(double a, double b, double c, double d)
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{
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double[] roots = null;
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roots = new double[3];
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double f = ((3 * c / a) - ((b * b) / (a * a))) / 3;
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double g = ((2 * (b * b * b) / (a * a * a)) - (9 * b * c / (a * a)) + (27 * d / a)) / 27;
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double h = ((g * g) / 4) + ((f * f * f) / 27);
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if (h > 0)
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{
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double r = -(g / 2) + Math.Sqrt(h);
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double s = Math.Sign(r) * Math.Pow(Math.Abs(r), (1 / 3.0));
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double t = -(g / 2) - Math.Sqrt(h);
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double u = Math.Sign(t) * Math.Pow(Math.Abs(t), (1 / 3.0));
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roots[0] = (s + u) - (b / (3 * a));
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roots[1] = -1;
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roots[2] = -1;
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}
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else if (f == 0 && g == 0 && h == 0)
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{
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roots[0] = Math.Pow((d / a), 1 / 3.0) * -1;
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roots[1] = roots[0];
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roots[2] = roots[0];
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}
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else
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{
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double i = Math.Sqrt(((g * g) / 4) - h);
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double j = Math.Pow(i, (1 / 3.0));
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double k = Math.Acos(-(g / (2 * i)));
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double l = j * -1;
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double m = Math.Cos(k / 3);
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double n = Math.Sqrt(3) * Math.Sin(k / 3);
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double p = (b / (3 * a)) * -1;
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roots[0] = 2 * j * Math.Cos(k / 3) - (b / (3 * a));
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roots[1] = l * (m + n) + p;
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roots[2] = l * (m - n) + p;
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}
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return roots?.ToList();
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}
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public static List<double> Solve(double a, double b, double c, double d, double e)
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{
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double x = 0; // Initial guess
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double epsilon = 1e-7; // Precision
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double diff = 1;
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double maxRoot = -1;
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List<double> roots = new List<double>();
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while (diff > epsilon)
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{
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double x2 = x * x;
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double x3 = x2 * x;
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double x4 = x2 * x2;
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double f = a * x4 + b * x3 + c * x2 + d * x + e;
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double df = 4 * a * x3 + 3 * b * x2 + 2 * c * x + d;
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double x1 = x - f / df;
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diff = Math.Abs(x1 - x);
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x = x1;
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if (x > maxRoot)
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{
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maxRoot = x;
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}
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}
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if (maxRoot < 0) roots = null;
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else roots.Add(maxRoot);
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return roots;
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}
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}
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}
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