Basic Iteration Method

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

double h(double a){return (  1 + 2*sin(a/57.2957795)  ) / 2;}

int main(void)
{
     double xsifir, epsilon, fark;
     printf( "X0 = " ); scanf( "%lf" , &xsifir );
     printf( "epsilon = " ); scanf( "%lf" , &epsilon );

     printf( abs( cos( xsifir/57.2957795 )  < 1)  ? "\nYakinsaktir.\n\n" : "\nIraksaktir.\n\n");

     do{
        fark = xsifir-h(xsifir);
        printf("fark = %.20lf , kok = %.16lf\n", fark, h(xsifir));
        if( fark > epsilon ){ xsifir = h(xsifir); }
     } while ( fark > epsilon );

     return 0;
}