function - creating a Sin formula in c programming -

the program compile when running not getting correct values inputs, had looked way make sine formula , had found 1 don't believe right.

is formula correct? think running sin function in c giving me wrong value well.

* still getting wrong values these changes if input 1.5 , 4 im getting 0.000 , random integer

 /*   * function mysin using sin formula sin of x   * function returns sin value computed    * parameters -for function mysin "x" value sin   *            -"n"is number of series run   *   *the program uses sin(x) function real sin   *    */    #include <stdio.h>  #include <math.h>   int mysin(double x, int n){      int i=0;     double sinx=0;      for(i=1; i<=n; i+=2){         sinx=(pow(x,i)+sinx); //      }      return sinx;     }       int main(double sinx){      double realsin=0;      double x=0;     int n=0;      printf("please input x , n:");     scanf("%lf",&x);     scanf("%d",&n);      mysin(x,n);      realsin=sin(x);      printf("mysin= %f\n sin=%d\n",sinx,realsin);   } 

your mysin function wrong in @ least 5 separate ways. using ** represent exponentiation (to avoid confusion xor), correct formula is

sin(x) = x - x**3/3! + x**5/5! - x**7/7! + x**9/9! ... 

your implementation fails because

1. it discards previous terms on every iteration of loop.
2. it doesn't alternate signs.
3. it includes even-exponent terms.
4. it doesn't compute factorial in divisor.
5. the return type int, discarding fractional component of computed result.

furthermore, main wrong in several more ways. return value of mysin ignored. instead, sinx first argument main, number of command-line arguments program received (including name run as). also, %d used numbers in format strings, regardless of type, when it's meant int.

to fix mysin, have i go on odd values, , have every iteration of loop compute x**i/i! , add current value of sinx.

to fix main, declare local sinx variable in main , assign sinx = mysin(x, n) instead of declaring sinx argument. also, use %lf reading doubles scanf , %f writing doubles printf.