/*

*练习浮点数的运算

求一个一元二次方程的两个根

*/

public class calFloat

{

public static void main(String []args)

{

double a = 1.0;

double b = 3.0;

double c = -4.0;

double r1 = 0;

double r2 = 0;

double b24ac = b*b - 4*a*c;

if(b24ac >= 0)

{

r1 = (-b + Math.sqrt(b24ac))/(2*a);

r2 = (-b - Math.sqrt(b24ac))/(2*a);

System.out.println(r1);

System.out.println(r2);

System.out.println(r1 == 1 && r2 == -4 ? "测试通过" : "测试失败");

}

else

{

System.out.println("此方程无根");

}

}

}