Uncertainty Propagation in C++

Listing 3: Function uncertain_print()

//  prints  uncertainty  to  2  digits  and  value  to  same  precision
inline  void  uncertain_print(double  mean,  double  sigma,  ostream  &os  =  cout)
{
      int  original_precision  =  os.precision();
      long  original_format  =  os.flags(ios::showpoint);
      int  precision;
      //  special  cases  for  zero,  NaN,  and  Infinities
      //  (positive  &  negative)
      if  ((sigma  ==  0.0)  ||  (sigma  !=  sigma)  ||  (1.0/sigma  ==  0.0))
      {
            precision  =  0;
      }
      else
      {
            //  round  sigma  to  2  digits
            int  sigma_digits  =  1  -  int(floor(log10(fabs(sigma))));
            double  round_10_pow  =  pow(10.0,  sigma_digits);
            sigma  =  floor(sigma  *  round_10_pow  +  0.5)  /  round_10_pow;
            //  round  mean  to  same  #  of  digits
            mean  =  floor(mean  *  round_10_pow  +  0.5)  /  round_10_pow;
            if  (mean  ==  0.0)
            {
                  if  (sigma_digits  >  0)
                        precision  =  sigma_digits  +  1;
                  else
                        precision  =  1;
            }
            else
            {
                  precision  =  int(floor(log10(fabs(mean))))  +  sigma_digits  +  1;
                  if  (precision  <  1)
                  {
                      mean  =  0.0;
                      if  (sigma_digits  >  0)
                            precision  =  sigma_digits  +  1;
                      else
                            precision  =  1;
                  }
            }
      }
      os  <<  setprecision(precision)
            <<  mean  <<  "  +/-  "
            <<  setprecision(2)
            <<  sigma
            <<  setprecision(original_precision);
      os.flags(original_format);
}
//End of File