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

int main ( )
{
  double e;
  double r1;
  double r2;
  double s;

  printf ( "Enter S: " );
  scanf ( "%lf", &s );

  printf ( "Enter R1: " );
  scanf ( "%lf", &r1 );

  while ( 1 )
  {
    r2 = s / r1;
    e = fabs ( s - r1 * r1 );
    printf ( "  %24.16g  %24.16g  %g\n", r1, r2, e );
    if ( e < 0.000000001 )
    {
      printf ( "R1 is a good approximation!\n" );
      break;
    }
    r1 = ( r1 + r2 ) / 2;
  }

  return 0;
}