#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
#include "io_status.h"
#include "array.h"
#include "functions.h"

double solve5(double, double);

int main(int argc, char* argv[])
  {
  int task = 5;
  double x, eps;
  double res;
  double diff;
  double t;
  if (!((argc == 3) && sscanf(argv[1], "%le", &x) == 1 && sscanf(argv[2], "%le", &eps) == 1))
      {
      printf("Usage: %s x0 eps\n", argv[0]);
      return 1;
      }
  t = clock();
  res = solve5(x, eps);
  t = (clock() - t) / CLOCKS_PER_SEC;
  diff = fabs(res - sin(x));
  printf ("%s : Task = %d Result = %e Residual = %e Elapsed = %.2f\n", argv[0], task, res, diff, t);
  return 0;
  }
  
double solve5(double x, double eps)
    {
    int i = 1, sign = 1, flag = 0;
    double el, res = 0;
    x = fmod(x, 2 * M_PI);
    if (x > M_PI)
        {
        x = x - M_PI;
        sign *= -1;
        }
    if (x < -M_PI)
        {
        x = x + M_PI;
        sign *= -1;
        }
    if (x > M_PI / 2) x = M_PI - x;
    if (x < -M_PI / 2) x = -M_PI - x;
    if (x > M_PI / 4)
        {
        x = M_PI / 2 - x;
        flag = 1;
        }
    if (x < -M_PI / 4)
        {
        x = -M_PI / 2 - x;
        sign *= -1;
        flag = 1;
        }
    if (flag == 0)
        {
        el = x;
        while (fabs(el) >= eps)
            {
            res += el;
            el *= -1 * ((x * x) / (4 * i * i + 2 * i));
            i++;
            }
        }
    else
        {
        el = 1;
        while (fabs(el) >= eps)
            {
            res += el;
            el *= -1 * ((x * x) / (4 * i * i - 2 * i));
            i++;
            }
        }
    return sign * res;
    }