77 lines
1.8 KiB
C++
77 lines
1.8 KiB
C++
/* ----------------------------------------------------------------------------
|
|
|
|
* GTSAM Copyright 2010, Georgia Tech Research Corporation,
|
|
* Atlanta, Georgia 30332-0415
|
|
* All Rights Reserved
|
|
* Authors: Frank Dellaert, et al. (see THANKS for the full author list)
|
|
|
|
* See LICENSE for the license information
|
|
|
|
* -------------------------------------------------------------------------- */
|
|
|
|
/**
|
|
* @file Cyclic.h
|
|
* @brief Cyclic group, i.e., the integers modulo N
|
|
* @author Frank Dellaert
|
|
**/
|
|
|
|
#pragma once
|
|
|
|
#include <gtsam/base/Group.h>
|
|
#include <gtsam/base/Testable.h>
|
|
|
|
#include <cassert>
|
|
#include <iostream> // for cout :-(
|
|
|
|
namespace gtsam {
|
|
|
|
/// Cyclic group of order N
|
|
template<size_t N>
|
|
class Cyclic {
|
|
size_t i_; ///< we just use an unsigned int
|
|
public:
|
|
/// Constructor
|
|
Cyclic(size_t i) :
|
|
i_(i) {
|
|
assert(i < N);
|
|
}
|
|
/// Default constructor yields identity
|
|
Cyclic():i_(0) {
|
|
}
|
|
static Cyclic Identity() { return Cyclic();}
|
|
|
|
/// Cast to size_t
|
|
operator size_t() const {
|
|
return i_;
|
|
}
|
|
/// Addition modulo N
|
|
Cyclic operator+(const Cyclic& h) const {
|
|
return (i_ + h.i_) % N;
|
|
}
|
|
/// Subtraction modulo N
|
|
Cyclic operator-(const Cyclic& h) const {
|
|
return (N + i_ - h.i_) % N;
|
|
}
|
|
/// Inverse
|
|
Cyclic operator-() const {
|
|
return (N - i_) % N;
|
|
}
|
|
/// print with optional string
|
|
void print(const std::string& s = "") const {
|
|
std::cout << s << i_ << std::endl;
|
|
}
|
|
/// equals with an tolerance, prints out message if unequal
|
|
bool equals(const Cyclic& other, double tol = 1e-9) const {
|
|
return other.i_ == i_;
|
|
}
|
|
};
|
|
|
|
/// Define cyclic group to be a model of the Additive Group concept
|
|
template<size_t N>
|
|
struct traits<Cyclic<N> > : internal::AdditiveGroupTraits<Cyclic<N> >, //
|
|
Testable<Cyclic<N> > {
|
|
};
|
|
|
|
} // \namespace gtsam
|
|
|