jiefangcheng.java

求解方程式的根的算法

import java.math.*;
import java.io.*;
public class jiefangcheng{
 public static void main(String arg[]){
   int a,b,c;
   double x,x1,x2;
   String s;
   try{
      System.out.print("Enter a:");
      BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
      s=br.readLine();
      a=Integer.parseInt(s);
      System.out.print("Enter b:");
      s=br.readLine();
      b=Integer.parseInt(s);
      System.out.print("Enter c:");
      s=br.readLine();
      c=Integer.parseInt(s);
      if(a==0) { x=-c/b;
       System.out.println(x);
         }
      else {
          if((b*b-4*a*c)==0) {
                   x=(-b/(2*a));
                   System.out.println(x);
                          }
            else if((b*b-4*a*c)>0){
                  x1=((-b)+Math.sqrt(b*b-4*a*c))/(2*a);
                  x2=((-b)-Math.sqrt(b*b-4*a*c))/(2*a);
                   System.out.println(x1+"  "+x2);
                 }
                else System.out.println("无实数解");
}
 }catch(IOException e){}
}
}