inclusive_detached_dilepton/rounder.cpp

#include <iostream>

#include "TMath.h"

void println(std::string str) {
  std::cout << str << std::endl;
}

int get_ten_pow(double number) {
  int sign = 0;
  int pow = 0;
  if (number >= 1) {
    sign = 1;
    while (number >= 1) {
      // std::cout << number << " " << pow << std::endl;
      number = number / 10;
      pow++;
    }
  } else {
    sign = -1;
    while (number < 1) {
      number = number * 10;
      pow++;
    }
  }

  return sign * pow;
}

int get_decimals(double number) {
  int dec = 0;
  while ((int) number != number) {
    number = number * 10;
    dec++;
  }

  return dec;
}

int rounder() {
  // 2,543 ± 0,235 174,032 ± 82,543
  double val = 1.2456;// -> 4300
  double err = 0.2231; // -> 240

  std::cout << get_ten_pow(231.4345) << " " << get_ten_pow(0.0045)  << std::endl;

  int mv = 0;
  if (err < 1) {
    mv = 1;
  } else {
    mv = -1;
  }

  int pot = 0;
  while((mv == 1 && err < 3) || (mv == -1 && err > 30)) {
    err = err * TMath::Power(10, mv);
    pot++;
  }

  int err_ten_pow = get_ten_pow(err);
  int val_ten_pow = get_ten_pow(val);

  int diff = TMath::Abs(err_ten_pow - val_ten_pow);

  double input_err = err * TMath::Power(10, -mv * pot);
  double round_err = TMath::Ceil(err) * TMath::Power(10, -mv * pot);

  int err_dec = get_decimals(round_err);
  diff += err_dec;

  double mv_val = val * TMath::Power(10, mv * diff);

  double round_val = TMath::Ceil(mv_val) * TMath::Power(10, -mv * diff);

  std::cout << val << " " << mv_val << " "  << err << " " << input_err<< " " << std::endl;
  std::cout << val << "+-" << input_err << " -> " << round_val << "+-" << round_err << std::endl;
  return 0;
}