Question

报错Call of non-function in function main

程序很简单，就是计算几个值，TC2.0一直报错Call of non-function in function main ，还有两个warning：'FR' is assigned a value which is never used in function main
和 'FI' is assigned a value which is never used in function main
不懂啊，难道是我用sin函数用错了吗？？
#include<stdio.h>
#include<math.h>
#define pi 3.141592
void main()
{
double x[10]={0.1,.115194E+00,.147290E+00,.255190E+00,.437588E+00,.500000E+00,.615194E+00,.647290E+00,.755190E+00,.937588E+00};
double I[9],FR,FI;
int i;

for(i=1;i<9;i++)
{
FR=(sin(2*pi*i*x[1])-sin(2*pi*i*x[2])+sin(2*pi*i*x[3])-sin(2*pi*i*x[4])+sin(2*pi*i*x[5])-sin(2*pi*i*x[6])+sin(2*pi*i*x[7])-sin(2*pi*i*x[8])+sin(2*pi*i*x[9]))/(2*pi*i);
FI=(cos(2*pi*i*x[1])-cos(2*pi*i*x[2])+cos(2*pi*i*x[3])-cos(2*pi*i*x[4])+cos(2*pi*i*x[5])-cos(2*pi*i*x[6])+cos(2*pi*i*x[7])-cos(2*pi*i*x[8])+cos(2*pi*i*x[9]))/(2*pi*i);
I[i]=4(FR*FR+FI*FI);
printf("I(%d)=%f\n",i,I[i]);

}
}

Answer 1

I[i]=4(FR*FR+FI*FI);

应改为

I[i]=4*(FR*FR+FI*FI);

注意，C语言中乘号不可省略。