vertex.hpp

// Copyright (c) 2017--present, The Simons Foundation
// This file is part of TRIQS/ctint and is licensed under the terms of GPLv3 or later.
// SPDX-License-Identifier: GPL-3.0-or-later
// See LICENSE in the root of this distribution for details.
 
#pragma once
#include "./types.hpp"
#include <triqs/det_manip/det_manip.hpp>
 
namespace triqs_ctint {

  struct tau_t {

    static constexpr uint32_t n_max = std::numeric_limits<uint32_t>::max();

    static double beta;

    uint32_t n = 0;

    template <typename RNG> static tau_t get_random(RNG &rng) { return tau_t{rng(n_max)}; }

    operator double() const { return beta * double(n) / n_max; }
 
    // --- Comparison operators
    bool operator==(const tau_t &tau) const { return n == tau.n; }
    bool operator!=(const tau_t &tau) const { return n != tau.n; }
    bool operator<(const tau_t &tau) const { return n < tau.n; }
    bool operator>(const tau_t &tau) const { return n > tau.n; }
    bool operator<=(const tau_t &tau) const { return n <= tau.n; }
    bool operator>=(const tau_t &tau) const { return n >= tau.n; }

    friend std::ostream &operator<<(std::ostream &out, tau_t const &tau) {
      return out << double(tau) << " [tau_t : beta = " << tau.beta << " n = " << tau.n << "]";
    }

    static constexpr tau_t get_zero() { return tau_t{0}; }

    static constexpr tau_t get_zero_plus() { return tau_t{1}; }

    static constexpr tau_t get_zero_plus_plus() { return tau_t{2}; }

    static constexpr tau_t get_beta() { return tau_t{n_max}; }

    static constexpr tau_t get_beta_minus() { return tau_t{n_max - 1}; }

    static constexpr tau_t get_beta_minus_minus() { return tau_t{n_max - 2}; }
  };

  std::pair<double, double> cyclic_difference(tau_t const &tau1, tau_t const &tau2);
  std::pair<double, double> cyclic_difference(double tau1, double tau2);
 
  // Generate a tau_t-object from a double
  tau_t make_tau_t(double tau);

  struct vertex_idx_t {

    int b1, u1;

    int b2, u2;

    int b3, u3;

    int b4, u4;
  };
 
  std::ostream &operator<<(std::ostream &os, vertex_idx_t const &v);

  struct vertex_t {

    vertex_idx_t idx;

    tau_t tau1, tau2, tau3, tau4;

    U_scalar_t amplitude;

    double proposition_proba;

    int vertex_label = 0;

    int s = 0;
  };
 
  std::ostream &operator<<(std::ostream &os, vertex_t const &v);
 
} // namespace triqs_ctint