编写求解一元多次方程的解
package solve;
import java.io.*;
import java.util.*;
public class SolveEquation{
void print()throws IOException{char ch='y';
System.out.println("求解几次方程？1：一次 2：二次 3：三次");
Scanner sLine=new Scanner(System.in);
int pm=sLine.nextInt();
if(pm==1){
System.out.println("你选择的是一元一次方程:");
SolveEquation.SolveSimpleEquation fc=new SolveEquation().new
SolveSimpleEquation();
fc.SolveSimpleEquation();
}
else if(pm==2){
System.out.println("你选择的是一元二次方程:");
SolveEquation.SolveQuadraticEquation fc=new SolveEquation().new
SolveQuadraticEquation();
fc.SolveQuadraticEquation();
}
else if(pm==3){
System.out.println("你选择的是一元三次方程:");
SolveEquation.SolveCubicEquation fc=new SolveEquation().new SolveCubicEquation();
fc.SolveCubicEquation();
}
else {print();}
System.out.println("你是否想继续:(y/n)");
ch=(char)System.in.read();
System.in.skip(2);
if(ch=='y')print();
else if(ch=='n'){System.out.println("Good luck!");}
else print();
}
public static void main (String args[]) throws IOException{
SolveEquation se=new SolveEquation();
se.print();
}
interface I1{void SolveCubicEquation();}
interface I2{void SolveQuadraticEquation();}
interface I3{void SolveSimpleEquation();}
class SolveCubicEquation implements I1{
public void SolveCubicEquation(){
System.out.println("请输入形如一元三次方程mx^3+nx^2+tx+s=0的四个系数");
Scanner sce=new Scanner(System.in);
double m=sce.nextDouble();
double n=sce.nextDouble();
double t=sce.nextDouble();
double s=sce.nextDouble();
if(m==0)System.out.print("输入错误!");
else {
double a=n/m;
double b=t/m;
double c=s/m;
double q=(a*a-3*b)/9;
double r=(2*a*a*a-9*a*b+27*c)/54;
if(r*r
System.out.println("此方程有三个解:");
t=Math.acos(r/Math.sqrt(q*q*q));
double x1=-2*Math.sqrt(q)*Math.cos(t/3)-a/3;
double x2=-2*Math.sqrt(q)*Math.cos((t+2*Math.PI)/3)-a/3;
double x3=-2*Math.sqrt(q)*Math.cos((t-2*Math.PI)/3)-a/3;
System.out.println("x1="+x1+","+"x2="+x2+","+"x3="+x3);
}
else{
System.out.println("此方程只有一个解:");
int sgn=(r>=0)?1:-1;
double
u=-sgn*Math.pow((Math.abs(r)+Math.sqrt(r*r-q*q*q)),1./3);
double v=(u!=0)?q/u:0;
double x1=u+v-a/3;
System.out.println("x="+x1);
}
}
}
}
class SolveQuadraticEquation implements I2{
public void SolveQuadraticEquation(){
System.out.println("请输入形如一元二次方程ax^2+bx+c=0的三个系数");
Scanner sce=new Scanner(System.in);
double a=sce.nextDouble();
double b=sce.nextDouble();
double c=sce.nextDouble();
if(a==0)System.out.print("输入错误!");
else {
double d=b*b-4*a*c;
if(d>0){
double x1=(-b+Math.sqrt(d))/2*a;
double x2=(-b+Math.sqrt(d))/2*a; System.out.println("有两个实根x1="+x1+","+"x2="+x2);
}
else if(d==0){
System.out.println("有一个实根"+(-b/2*a));
}
else if(d
double Re=-b/(2*a);
double Im=Math.sqrt(-d)/(2*a);
System.out.println("实部="+Re+" "+"虚部="+Im);
}
}
}
}
class SolveSimpleEquation implements I3{
public void SolveSimpleEquation(){
System.out.println("请输入形如一元一次方程ax+b=0的两个系数");
Scanner sce=new Scanner(System.in);
double a=sce.nextDouble();
double b=sce.nextDouble();
if(a==0)System.out.print("输入错误!");
else {
System.out.println("方程的根是x="+(-b/a));
}
}
}
}