pat乙级1051

当结果中a或者b小于0，大于0.005时，保留两位小数会输出-0.00，但应输出0.00。

 #include <iostream>

 #include <math.h>

 using namespace std;

 int main()

 {

     double r1, p1, r2, p2;

     cin >> r1 >> p1 >> r2 >> p2;

     double a1 = r1 * cos(p1), b1 = r1 * sin(p1);

     double a2 = r2 * cos(p2), b2 = r2 * sin(p2);

     double a3 = a1 * a2 - b1 * b2;

     double b3 = a1 * b2 + b1 * a2;

     if (a3 > -0.005 && a3 < ) a3 = -a3;

     if (b3 > -0.005 && b3 < ) b3 = -b3;

     if (b3 < )

         printf("%.2f%.2fi", a3, b3);

     else

         printf("%.2f+%.2fi", a3, b3);

     return ;

 }