放置Math.toRadians的解決二次和三次方程

Question

我寫一個程序，它解決了無論是二次或三次方程。問題是我不知道我是否正確地放置了Math.toRadians。

的代碼如下：

public double[] getRaices(double a,double b, double c, double d) throws ComplexException { 
    if (a==0){ 
     double discriminante=Math.pow(c,2)+((-4)*b*d); 
     if(discriminante>=0){ 
      this.Raices[0]=(c*(-1)+Math.sqrt(discriminante))/(2*b); 
      this.Raices[1]=(c*(-1)-Math.sqrt(discriminante))/(2*b); 
     }else{ 
      throw new ComplexException("No hay solucion Real"); 
     } 

    } else{ 
     double f=((3*c/a)-(Math.pow(b,2)/Math.pow(a,2)))/3; 
     double g=((2*Math.pow(b,3)/Math.pow(a,3))-(9*b*c/Math.pow(a,2))+(27*d/a))/27; 
     double h=(Math.pow(g,2)/4)+(Math.pow(f,3)/27); 
     if(f+g+h==0){ 
      Raices [0]=Math.cbrt(d/a)*(-1); 
      Raices [1]=Math.cbrt(d/a)*(-1); 
      Raices [2]=Math.cbrt(d/a)*(-1); 
     }else{ 
      if(h<=0){ 
       double i=Math.sqrt((Math.pow(g,2)/4)-h); 
       double j=Math.cbrt(i); 
       double k=Math.acos(Math.toRadians(-1*(g/2*i))); 
       System.out.println(" "+k+" "); 
       double l=j*(0-1); 
       double m=Math.toRadians(Math.cos(Math.toRadians(k/3))); 
       System.out.println(" "+m+" "); 
       double n=Math.sqrt(3)*Math.sin(Math.toRadians(k/3)); 
       System.out.println(" "+n+" "); 
       double p=(b/(3*a)*(0-1)); 
       Raices [0]=2*j*Math.cos(Math.toRadians(k/3))-(b/(3*a)); 
       Raices [1]=(l*(m+n))+p; 
       Raices [2]=(l*(m-n))+p; 
      }else{ 
       double r=((0-1)*(g/2))+Math.sqrt(h); 
       double s=Math.cbrt(r); 
       double t=((0-1)*(g/2))-Math.sqrt(h); 
       double u=Math.cbrt(t); 
       throw new ComplexException("2 de las raices son imaginarias pero una raiz es real: "+Math.floor(Raices [0]=(s+u)-(b/(3*a)))); 
      } 
     } 
    } 
    return Raices; 
} 

但問題是在if (h<=0)。

Answer 1

我測試你的代碼對網頁，發現了幾個錯誤。 首先是克/ 2I，你寫的G */2，而不是我克/ 2/I或（g /（2 * I）。而數Math.toRadians沒有必要（網頁說是計算弧度，所以沒必要轉換）

我添加的println幫助公式如下：

package test; 

public class Cubic { 
    private double[] Raices = new double[3]; 

    public static void main(String[] args) throws ComplexException { 
     double[] raices = new Cubic().getRaices(2, -4, -22, 24); 
     System.out.println(raices[0] + "," + raices[1] + "," + raices[2]); 
    } 

    public double[] getRaices(double a, double b, double c, double d) throws ComplexException { 
     if (a == 0) { 
      double discriminante = Math.pow(c, 2) + ((-4) * b * d); 
      if (discriminante >= 0) { 
       this.Raices[0] = (c * (-1) + Math.sqrt(discriminante))/(2 * b); 
       this.Raices[1] = (c * (-1) - Math.sqrt(discriminante))/(2 * b); 
      } else { 
       throw new ComplexException("No hay solucion Real"); 
      } 

     } else { 
      double f = ((3 * c/a) - (Math.pow(b, 2)/Math.pow(a, 2)))/3; 
      System.out.println("f=" + f); 
      double g = ((2 * Math.pow(b, 3)/Math.pow(a, 3)) - (9 * b * c/Math.pow(a, 2)) + (27 * d/a))/27; 
      System.out.println("g=" + g); 
      double h = (Math.pow(g, 2)/4) + (Math.pow(f, 3)/27); 
      System.out.println("h=" + h); 
      if (f + g + h == 0) { 
       Raices[0] = Math.cbrt(d/a) * (-1); 
       Raices[1] = Math.cbrt(d/a) * (-1); 
       Raices[2] = Math.cbrt(d/a) * (-1); 
      } else { 
       if (h <= 0) { 
        double i = Math.sqrt((Math.pow(g, 2)/4) - h); 
        double j = Math.cbrt(i); 
        double k = Math.acos(-1 * (g/2/i)); 
        System.out.println("k=" + k + " "); 
        double l = j * (0 - 1); 
        System.out.println("l=" + l + " "); 
        double m = Math.cos(k/3); 
        System.out.println("m= " + m + " "); 
        double n = Math.sqrt(3) * Math.sin(k/3); 
        System.out.println("n= " + n + " "); 
        double p = (b/(3 * a) * (0 - 1)); 
        System.out.println("p= " + p + " "); 
        Raices[0] = 2 * j * Math.cos(k/3) - (b/(3 * a)); 
        Raices[1] = (l * (m + n)) + p; 
        Raices[2] = (l * (m - n)) + p; 
       } else { 
        double r = ((0 - 1) * (g/2)) + Math.sqrt(h); 
        double s = Math.cbrt(r); 
        double t = ((0 - 1) * (g/2)) - Math.sqrt(h); 
        double u = Math.cbrt(t); 
        throw new ComplexException(
          "2 de las raices son imaginarias pero una raiz es real: " + Math.floor(Raices[0] = (s + u) - (b/(3 * a)))); 
       } 
      } 
     } 
     return Raices; 
    } 
}