#include "stdio.h"
#include "stdlib.h"
//#include "math.h"

int factorial(int x);
double mypow(double x,int y);
double sin(double x);
//double arctan(double x);
//float ln(float x);

int main() {

   double resultsin;
  // double resultarctan;
   resultsin=sin(90);
  // //resultarctan=arctan(1);
   printf("Der Sinus von 90 ist: %.16f\n",resultsin );
  // //printf("Der arctan von 90 ist: %.16f\n",resultarctan );

    return 0;
}


int factorial(int x){
  if (x == 1)
    return (1);
  else
    return (x * factorial(x-1));
}

double mypow(double x,int y){ // x-basis ; y-exponent
double a;
if (y==0){
  return 1;
}
else if (y==1){
  return x;
}
else if (y > 0){
  a=x;
  while (y-- > 1) {
    a =a*x;
  }
  return a;
}
  else if(y < 0){
    a=x;
    while (y++ < -1) {
      a = a*x;
    }
    a = 1/a;
    return a;
  }

return 0;
}


double sin(double x)
{
  double erg;
  double k=10;

  erg=(mypow(-1,k)) * ((mypow(x,(2*k+1))) / (factorial((2*k+1))));

return erg;
}

// double arctan(double x){
//   double erg;
//   double k=0;
//
//   erg=mypow(-1,k) * (mypow(x,(2*k+1)))/(2*k+1);
//
//   return erg;
// }