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

int
main (int argc, char *argv[])
{
  double x1, x2;
  double p, q;
  double epsm, cond;

  x1 = 1.0;
  printf ("x1 esatto =  %20.18lf\n", x1);
  x2 = 1.0 + 1.0/(7*7*7*7*7);

  p = (x1 + x2)/2.0;
  q = x1 * x2;

  x1 = p - sqrt (p*p - q);
  printf ("(alg 1) x1 = %20.18lf\n", x1);

  x1 = q/(p + sqrt (p*p - q));
  printf ("(alg 2) x1 = %20.18lf\n", x1);

  epsm = 1.07309e-16;
  cond = 2/sqrt(p*p-q);
  printf ("Indice di condizionamento circa K = %lg\n", cond);
  printf ("Errore atteso: K*%20.18lf =\n", epsm);
  printf ("             %20.18lf\n", epsm*cond);
  return (0);
}