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 ;
 }