求大神指导，不知哪里有问题

#include<stdio.h>
#include<math.h>
int main()
{
int situation;
double x,y,Z,e=2.71828;
scanf("%1f,%1f",&x,&y);
printf("请选择x,y的情况\n");
printf("(1:x>0&&y>0,2:x<0&&y>0,3:x<0&&y<0,4:x>0&&y<0):\n");
scanf("%d",&situation);
switch(situation){
case 1:Z=log(x)+log(y);break;
case 2:Z=sin(x)+cos(y);break;
case 3:Z=pow(e,2*x)+pow(e,3*y);break;
case 4:Z=tan(x+y);
}
printf("Z=%f\n",Z);
return 0;
求一个分段函数！I