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 < 0) a3 = -a3;
    if (b3 > -0.005 && b3 < 0) b3 = -b3;
    if (b3 < 0)
        printf("%.2f%.2fi", a3, b3);
    else
        printf("%.2f+%.2fi", a3, b3);
    return 0;
}