GSL浮点IEEE标准2

#include <stdio.h>#include <gsl/gsl_math.h>#include <gsl/gsl_ieee_utils.h>#pragma comment(lib, "libgsl_d.lib")#pragma comment(lib, "libgslcblas_d.lib")intmain (void){  double x = 1, oldsum = 0, sum = 0;   int i = 0;  gsl_ieee_env_setup (); /* read GSL_IEEE_MODE */  do     {      i++;            oldsum = sum;      sum += x;      x = x / i;            printf ("i=%2d sum=%.18f error=%g\n",              i, sum, sum - M_E);      if (i > 30)         break;    }    while (sum != oldsum);  return 0;}