作者cxzdsa5566 (cxzdsa5566)
看板Programming
标题Re: [问题] 小新手程式写不出来，麻烦高手帮忙。
时间Wed Oct 6 23:05:00 2010
#include <iostream>
#include <math.h>
using namespace std;
int main()
{
double a,b,c,z1,z2,z3,z2i,z3i,sita;
cout<<" This program finds the roots of x^3 +a x^2 + b x + c =0 "<<endl;
cout<<" Enter the coefficient a: "; cin>>a;
cout<<" Enter the coefficient b: "; cin>>b;
cout<<" Enter the constant c: "; cin>>c;
double Q=(3*b*b-a*a)/9;
double R=(9*a*b-27*c-2*a*a*a)/54;
double D=(Q*Q*Q+R*R*R)/3;
if(D==0) {
z1 = -a/3+2*pow(R,1.0/3.0);
z2 = z3=-a/3+2*sqrt(-Q);
z2i=z3i=0;
}
if (D>0) {
z1 = -a/3+pow((R+sqrt(D)),1.0/3.0)+pow((R-sqrt(D)),1.0/3.0);
z2 = -a/3-(pow(R+sqrt(D),1.0/3.0)+pow(R-sqrt(D),1.0/3.0))/2;
z2i =(pow(R+sqrt(D),1.0/3)-pow(R-sqrt(D),1.0/3.0))*(sqrt(3)*0.5);
z3 = -a/3-(pow(R+sqrt(D),1.0/3.0)+pow(R-sqrt(D),1.0/3.0))/2;
z3i = -(pow(R+sqrt(D),1.0/3.0)-pow(R-sqrt(D),1.0/3.0))*(sqrt(3)*0.5);
}
if (D<0) {
double sita=acos(R/sqrt(-Q*Q*Q));
z1=-a/3+2*sqrt(-Q)*cos(sita/3);
z2=-a/3+2*sqrt(-Q)*cos(sita/3+2*M_PI/3);
z3=-a/3+2*sqrt(-Q)*cos(sita/3+4*M_PI/3);
z2i=z3i=0;
}
cout<<endl;
cout<<" "<<"x^3+"<<a<<" x^2+ "<<b<<" x+ "<<c<<" = 0"<<endl;
cout<<" Root 1: "<<z1<<endl;
cout<<" Root 2: "<<z2<<" + "<<z2i<<"i"<<endl;
cout<<" Root 3: "<<z3<<" + "<<z3i<<"i"<<endl;
system("pause");
return 0;
}
这是最新改好的，
跑出来还是不对，
结果都会写啥#IND的，
都不是答案，
不过如果a=b=c=0
会算队就是@@
可以再帮帮忙吗?
--
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◆ From: 140.112.218.123
1F：嘘 ericinttu:小改版就要麻烦人debug,有没有这麽好的 59.117.120.133 10/06 23:21
2F：→ ericinttu:事? 59.117.120.133 10/06 23:21
4F：嘘 cooper6334:你应该去C++版，那边好人比较多 112.104.57.123 10/07 22:17
5F：→ cooper6334:pow(负数,小数次方)是算不出来的 112.104.57.123 10/07 22:34
6F：推 RedHouse:义大利面条不好吃 123.204.113.64 10/08 07:18
7F：→ horngsh:只爱写程式,不爱DEBUG的人撑不久112.104.191.119 10/08 08:26
8F：→ LPH66:那边好人其实是近一阵子比较多 XD 140.112.28.92 10/08 13:35