Grid1D.h

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#ifndef Grid1D_H
#define Grid1D_H
#include <cmath>
#include <algorithm>
#include "FWCore/Utilities/interface/Visibility.h"

class dso_internal Grid1D {
public:
  typedef float Scalar;
  //  typedef double Scalar;

  Grid1D() {}

  Grid1D(Scalar lower, Scalar upper, int nodes) : lower_(lower), upper_(upper), edges_(nodes - 2) {
    stepinv_ = (nodes - 1) / (upper - lower);
  }

  Scalar step() const { return 1. / stepinv_; }
  Scalar lower() const { return lower_; }
  Scalar upper() const { return upper_; }
  int nodes() const { return edges_ + 2; }
  int cells() const { return edges_ + 1; }

  Scalar node(int i) const { return i * step() + lower(); }

  bool inRange(int i) const { return i >= 0 && i <= edges_; }

  // return index and fractional part...
  int index(Scalar a, Scalar& f) const {
    Scalar b;
    f = modff((a - lower()) * stepinv_, &b);
    return b;
  }

  // move index and fraction in range..
  void normalize(int& ind, Scalar& f) const {
    if (ind < 0) {
      f -= ind;
      ind = 0;
    } else if (ind > edges_) {
      f += ind - edges_;
      ind = edges_;
    }
  }

  Scalar closestNode(Scalar a) const {
    Scalar b = (a - lower()) / step();
    Scalar c = floor(b);
    Scalar tmp = (b - c < 0.5) ? std::max(c, 0.f) : std::min(c + 1.f, static_cast<Scalar>(nodes() - 1));
    return tmp * step() + lower();
  }

  int index(Scalar a) const {
    int ind = static_cast<int>((a - lower()) / step());
    // FIXME: this causes an exception to be thrown later. Should be tested
    // more carefully before release
    //  if (ind < -1 || ind > cells()) {
    //     std::cout << "**** ind = " << ind << " cells: " << cells() << std::endl;
    //    return -1;
    //  }
    return std::max(0, std::min(cells() - 1, ind));
  }

private:
  Scalar stepinv_;
  Scalar lower_;
  Scalar upper_;
  int edges_;  // number of lower edges = nodes-2...
};

#endif