arctg x

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

typedef struct
{
    double value;
    int elnum;
    int precreached;
} Result;

Result arctg(double x, double eps, int m);

int main(int argc, char ** argv)
{
    double dx;
    double precision;
    int m;
    double x;
    Result tempresult;

    puts("Enter dx");
    fflush(stdin);
    if(scanf("%lf", &dx) == EOF)
        return 1;

    puts("Enter precision");
    fflush(stdin);
    if(scanf("%lf", &precision) == EOF)
        return 1;

    puts("Enter number of samples");
    fflush(stdin);
    if(scanf("%d", &m) == EOF)
        return 1;

    //dx = 0.01l;
    //precision = 0.0000000000000000000000000000000000000000000000000000000001l;
    //m = 1000;

    x = -1.0l;

    while((x += dx) < 1.0f)
    {
        tempresult = arctg(x, precision, m);

        printf("%8.5f, %15.12f, arctg, %5d, PRECISION %s\n",
                x,
                tempresult.value,
                tempresult.elnum,
                (tempresult.precreached ?
                    "REACHED" : "NOT REACHED"));
    }
    return 0;
}

Result arctg(double x, double eps, int m)
{
    int i;
    double delta = 2 * eps;
    Result result;
    result.value = 0l;

    for(i = 0; i < m && fabs(delta) >= eps; i++)
    {
        delta = pow(-1, i) * (pow(x, (2 * i) + 1)) / ((2 * i) + 1);
        result.value += delta;
    }

    if(fabs(delta) < eps)
        result.precreached = 1;
    else
        result.precreached = 0;

    result.elnum = i;
    return result;
}