View Compilation Error

0_0_13976613_5778.cpp: In function 'int main()':
0_0_13976613_5778.cpp:30:71: error: expected ',' or ';' before ')' token
    double temp = fabs(num[i].y-num[i-1].y)/double(num[i].x-num[i-1].x));
                                                                       ^