Fourier transformation in C

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C

#include <stdio.h>
#include <math.h>
#include <stdlib.h>

void main()
{

    int func (double x[], int n);
    int N,i,t,n,m;
    double f;
    printf("input N\n");
    scanf(" %d",&N);
    printf("f=%lf\n",f);
    printf("t=%lf\n",t);

    double PI= 4.0*atan(1.0);

    for(i=1; i<=N; i+2);
    {
        for(t=0; t<=n; t++);
        {
        srand(time(NULL));
        double f = rand();

     x[t]=(4/PI)*((1/i)*sin(2*i*PI*f*t));
     x[t]>-10||x<10;
    }
    }


}

Here is My code to such a task https://imagizer.imageshack.us/v2/1244x699q90/673/af9sg9.jpg[^]

Could you tell me where am I wrong for Part 1?

It is in the formula that it icreases by 2, so how should I store it?
Now I have something like this

#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include "time.h"

int func(double x[], int n);
int main()
{

int func (double x[], int n);
int N,i,t,n,m;
double f,x[1000];
printf("input N\n");
scanf(" %d",&N);


double PI= 4.0*atan(1.0);

for(i=1; i<=N; i+2)
{
for(t=0; t<=n; t++)
{
srand(time(NULL));
double f = rand();


x[t]=(4/PI)*((1/i)*sin(2*i*PI*f*t));

if(x[t]>-10||x<10)
printf("%lf\n",x[t]);
}
}

return 0;
}

So I think I have come up with part 1 solution, but I am still figuring out part 2
I have this so far, can you point me where I am wrong?

#include <stdio.h>
#include <math.h>
#include "winbgi2.h"
#include "time.h"
#include <stdlib.h>

int main()
{	int N ;
printf("input N\n");
	scanf(" %d",&N);
	graphics(1000,200);
int n = 10000;
double f = 0.01;
double PI= 4.0*atan(1.0);
 
for(int t=0; t<=n; t++)
{
double y;
y=(4/PI)*sin(2*PI*f*t);
 int p;
 if (y>0)
 p=50;
 
 else
 p=70;
circle(t,p,1);
}
	wait();

	

	for(int i=1; i<=N; i+2)
	{
		for(int t=0; t<=n; t++)
		{
		
     double x;
	 x=(4/PI)*((1/i)*sin(2*i*PI*f*t));
	 circle(t,x,1);
		}
	}
return 0;
}