#include "TGraph.h"

#include <fstream>
#include <iostream>

double runR(double evalTime) {
  static TGraph *g = ((TGraph *)0);
  if (!g) {
    // "import" data from output/histogram304.txt
    g = new TGraph();
    double x, y;
    std::ifstream fin("output/histogram304.txt");
    while (fin >> y) {
      x = g->GetN() * 0.18 / 100.;
      g->SetPoint(g->GetN(), x, y); // "append" point
    }
    // std::cout << "... " << g->GetN() << " points found ..." << std::endl;
    g->Draw("AL*");
  }
  double r = g->Eval(evalTime);
  return r;
}

void calcR(double t = 0.05) { // "time" for evaluation
  double rg = runR(t);
  std::cout << "t = " << t << " µs →  r = " << rg << " mm" << std::endl;
}